Isometric Tension Measurements Research Articles

Pulmonary surfactant and prostaglandin E2 in airway smooth muscle relaxation of human and male guinea pigs.

Pulmonary surfactant serves as a barrier to respiratory epithelium but can also regulate airway smooth muscle (ASM) tone. Surfactant (SF) relaxes contracted ASM, similar to β2-agonists, anticholinergics, nitric oxide, and prostanoids. The exact mechanism of surfactant relaxation and whether surfactant relaxes hyperresponsive ASM remains unknown. Based on previous research, relaxation requires an intact epithelium and prostanoid synthesis. We sought to examine the mechanisms by which surfactant causes ASM relaxation. Organ bath measurements of isometric tension of ASM of guinea pigs in response to exogenous surfactant revealed that surfactant reduces tension of healthy and hyperresponsive tracheal tissue. The relaxant effect of surfactant was reduced if prostanoid synthesis was inhibited and/or if prostaglandin E2-related EP2 receptors were antagonized. Atomic force microscopy revealed that human ASM cells stiffen during contraction and soften during relaxation. Surfactant softened ASM cells, similarly to the known bronchodilator prostaglandin E2 (PGE2) and the cell softening was abolished when EP4 receptors for PGE2 were antagonized. Elevated levels of PGE2 were found in cultures of normal human bronchial epithelial cells exposed to pulmonary surfactant. We conclude that prostaglandin E2 and its EP2 and EP4 receptors are likely involved in the relaxant effect of pulmonary surfactant in airways.

Methylglyoxal induces endothelial cell apoptosis and coronary microvascular dysfunction through regulating AR-cPLA2 signaling

ObjectiveSince diabetic patients with coronary microvascular dysfunction (CMD) exhibit high cardiac mortality and women have higher prevalence of non-obstructive coronary artery disease than men, we tried to expand the limited understanding about the etiology and the sex difference of diabetic CMD. Approach and resultsAccumulated methylglyoxal (MGO) due to diabetes promotes vascular damage and it was used for mimicking diabetic status. Flow cytometry analysis and isometric tension measurement were performed to evaluate coronary artery endothelial injury. MGO induced apoptosis of coronary endothelial cells, accompanied by downregulation of androgen receptor (AR). Lentivirus-mediated stable expression of AR in coronary endothelial cells increased anti-apoptotic Bcl-2 expression and attenuated MGO-induced cell apoptosis. cPLA2 activation was the downstream of AR downregulation by MGO treatment. Moreover, MGO also activated cPLA2 rapidly to impair endothelium-dependent vasodilation of coronary arteries from mice. Reactive oxygen species (ROS) overproduction was demonstrated to account for MGO-mediated cPLA2 activation and endothelial dysfunction. Importantly, AR blockade increased endothelial ROS production whereas AR activation protected coronary artery endothelial vasodilatory function from the MGO-induced injury. Although galectin-3 upregulation was confirmed by siRNA knockdown in endothelial cells not to participate in MGO-induced endothelial apoptosis, pharmacological inhibitor of galectin-3 further enhanced MGO-triggered ROS generation and coronary artery endothelial impairment. ConclusionsOur data proposed the AR downregulation-ROS overproduction-cPLA2 activation pathway as one of the mechanisms underlying diabetic CMD and postulated a possible reason for the sex difference of CMD-related angina. Meanwhile, MGO-induced galectin-3 activation played a compensatory role against coronary endothelial dysfunction.

Evidence for the involvement of TRPV2 channels in the modulation of vascular tone in the mouse aorta

AimsTransient receptor potential vanilloid 2 (TRPV2) channels are expressed in both smooth muscle and endothelial cells and participate in vascular mechanotransduction and sensing of high temperatures and lipids. Nevertheless, the impact of TRPV2 channel activation by agonists on the coordinated and cell-type specific modulation of vasoreactivity is unknown. Main methodsAorta from 2- to 4-months-old male Oncins France 1 mice was dissected and mounted in tissue baths for isometric tension measurements. TRPV2 channel expression was assessed by immunofluorescence and western blot in mice aortas and in cultured A7r5 rat aortic smooth muscle cells. Key findingsTRPV2 channels were expressed in all three mouse aorta layers. Activation of TRPV2 channels with probenecid evoked endothelium-dependent relaxations through a mechanism that involved activation of smooth muscle Kir and Kv channels. In addition, TRPV2 channel inhibition with tranilast increased endothelium-independent relaxations to probenecid and this effect was abrogated by the KATP channel blocker glibenclamide, revealing that smooth muscle TRPV2 channels induce negative feedback on probenecid relaxations mediated via KATP channel inhibition. Exposure to the NO donor sodium nitroprusside increased TRPV2 channel translocation to the plasma membrane in cultured smooth muscle cells and enhanced negative feedback on probenecid relaxations. SignificanceIn conclusion, we present the first evidence that TRPV2 channels may modulate vascular tone through a balance of opposed inputs from the endothelium and the smooth muscle leading to net vasodilation. The fact that TRPV2 channel-induced activity can be amplified by NO emphasizes the pathophysiological relevance of these findings.

Aloperine protects pulmonary hypertension via triggering PPARγ signaling and inhibiting calcium regulatory pathway in pulmonary arterial smooth muscle cells.

Previous studies have reported the beneficial role of Aloperine (ALO), an active vasodilator purified from the seeds and leaves of the herbal plant Sophora alopecuroides L., on experimental pulmonary hypertension (PH); however, detailed mechanisms remain unclear. In this study, monocrotaline-induced PH (MCT-PH) rat model and primarily cultured rat distal pulmonary arterial smooth muscle cells (PASMCs) were used to investigate the mechanisms of ALO on experimental PH, pulmonary vascular remodeling, and excessive proliferation of PASMCs. Results showed that first, ALO significantly prevented the disease development of MCT-PH by inhibiting right ventricular systolic pressure (RVSP) and right ventricular hypertrophy indexed by the Fulton Index, normalizing the pulmonary arterials (PAs) remodeling and improving the right ventricular function indexed by transthoracic echocardiography. ALO inhibited the excessive proliferation of both PAs and PASMCs. Then, isometric tension measurements showed vasodilation of ALO on precontracted PAs isolated from both control and MCT-PH rats via activating the KCNQ channel, which was blocked by specific KCNQ potassium channel inhibitor linopirdine. Moreover, by using immunofluorescence staining and nuclear/cytosol fractionation, we further observed that ALO significantly enhanced the PPARγ nuclear translocation and activation in PASMCs. Transcriptome analyses also revealed activated PPARγ signaling and suppressed calcium regulatory pathway in lungs from MCT-PH rats treated with ALO. In summary, ALO could attenuate MCT-PH through both transient vasodilation of PAs and chronic activation of PPARγ signaling pathway, which exerted antiproliferative roles on PASMCs and remodeled PAs.NEW & NOTEWORTHY Aloperine attenuates monocrotaline-induced pulmonary hypertension (MCT-PH) in rats by inhibiting the pulmonary vascular remodeling and proliferation of pulmonary arterial smooth muscle cells (PASMCs). In mechanism, Aloperine not only exerts a transient KCNQ-dependent vasodilation in precontracted pulmonary arteries (PAs) from both control and MCT-PH rats but also activates PPARγ nuclear translocation and signaling transduction in PASMCs, which chronically inhibits the calcium regulatory pathway and proliferation of PASMCs.

Tocolytic Effect of White Pepper (Piper nigrum Linn.) on Isolated Rat Uterine Contraction in vitro

Piper nigrum Linn. (Pepper) is a very well-known spice used for different purposes such as human dietaries, medicine and preservative. In Thai traditional medicine, white pepper is a component of herbal formulas used to treat many disorders including symptoms of dysmenorrhea. It is of interest to investigate the effect of methanolic extract of white pepper (MEWP) on the isolated rat uterus contractions induced by various uterine stimulants and the possible mechanism(s) involved. Strips of uterus were prepared from estrogen-primed female Wistar rats, fixed in the organ bath filled with an appropriate physiological solution with carbogen bubbled continuously at 37 °C. The measurement of isometric tension was then performed using force transducer attached to a polygraph. MEWP was tested its effect on the uterine contraction and found the inhibitory effects on the contraction induced by oxytocin, PGF2α and depolarizing solution. TEA inhibited the uterine relaxing effect of MEWP while glibenclamide had no effects when the uterus was induced to contract with oxytocin. Propranolol abolished the uterine relaxing effect of isoproterenol while it had no effects on the relaxing effect of MEWP. The results suggested that MEWP is likely to be a general uterine relaxant. The effects may be due to the interference on Ca2+ influx into the uterine muscle cells which may involve the opening of KCa channel. The effect was unlikely to occur via the KATP-channel and may not involve the interaction of MEWP on b-adrenergic receptor on the uterine muscle cells. HIGHLIGHTS Methanolic extract of white pepper (MEWP) is likely to be a general uterine relaxant. The uterine relaxing effect of MEWP may involve an inhibition of a rise in intracellular Ca2+ from both Ca2+ influx via plasma membrane of the uterine smooth muscle cell and probably Ca2+ release from internal storage. The effect of MEWP may be mediated mainly through a reduction in Ca2+ influx, possibly through voltage dependent Ca2+ The effect of MEWP may involve with the opening of KCa channel, which may arise from direct action of MEWP on the calcium channel or be a consequence of an increase in [Ca2+]i. The uterine relaxing effect of MEWP is unlikely to be mediated by an activation of β2 –adrenergic receptor. GRAPHICAL ABSTRACT

Receptor-specific contributions of caveolae, PKC, and Src tyrosine kinase to serotonergic and adrenergic regulation of Kv channels and vasoconstriction

AimsCaveolae are invaginated, Ω-shaped membrane structures. They are now recognized as portals for signal transduction of multiple chemical and mechanical stimuli. Notably, the contribution of caveolae has been reported to be receptor-specific. However, details of how they differentially contribute to receptor signaling remain unclear. Main methodsUsing isometric tension measurements, patch-clamping, and western blotting, we examined the contribution of caveolae and their related signaling pathways to serotonergic (5-HT2A receptor-mediated) and adrenergic (α1-adrenoceptor-mediated) signaling in rat mesenteric arteries. Key findingsDisruption of caveolae by methyl-β-cyclodextrin effectively blocked vasoconstriction mediated by the 5-HT2A receptor (5-HT2AR), but not by the α1-adrenoceptor. Caveolar disruption selectively impaired 5-HT2AR-mediated voltage-dependent K+ channel (Kv) inhibition, but not α1-adrenoceptor-mediated Kv inhibition. In contrast, both serotonergic and α1-adrenergic effects on vasoconstriction, as well as Kv currents, were similarly blocked by the Src tyrosine kinase inhibitor PP2. However, inhibition of protein kinase C (PKC) by either GO6976 or chelerythrine selectively attenuated the effects mediated by the α1-adrenoceptor, but not by 5-HT2AR. Disruption of caveolae decreased 5-HT2AR-mediated Src phosphorylation, but not α1-adrenoceptor-mediated Src phosphorylation. Finally, the PKC inhibitor GO6976 blocked Src phosphorylation by the α1-adrenoceptor, but not by 5-HT2AR. Significance5-HT2AR-mediated Kv inhibition and vasoconstriction are dependent on caveolar integrity and Src tyrosine kinase, but not on PKC. In contrast, α1-adrenoceptor-mediated Kv inhibition and vasoconstriction are not dependent on caveolar integrity, but rather on PKC and Src tyrosine kinase. Caveolae-independent PKC is upstream of Src activation for α1-adrenoceptor-mediated Kv inhibition and vasoconstriction.

MP27-06 BROMELAIN INDUCES RELAXATION OF HUMAN CORPUS CAVERNOSUM TISSUE IN VITRO INDEPENDENT NITRIC OXIDE-CGMP PATHWAY: POSSIBLE SIGNIFICANCE FOR ERECTILE DYSFUNCTION

You have accessJournal of UrologyCME1 Apr 2023MP27-06 BROMELAIN INDUCES RELAXATION OF HUMAN CORPUS CAVERNOSUM TISSUE IN VITRO INDEPENDENT NITRIC OXIDE-CGMP PATHWAY: POSSIBLE SIGNIFICANCE FOR ERECTILE DYSFUNCTION Serap Gur, Suresh C. Sikka, Asim B. Abdel-Mageed, Didem Yilmaz-Oral, Sudha Talwar, and Wayne J.G. Hellstrom Serap GurSerap Gur More articles by this author , Suresh C. SikkaSuresh C. Sikka More articles by this author , Asim B. Abdel-MageedAsim B. Abdel-Mageed More articles by this author , Didem Yilmaz-OralDidem Yilmaz-Oral More articles by this author , Sudha TalwarSudha Talwar More articles by this author , and Wayne J.G. HellstromWayne J.G. Hellstrom More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003255.06AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Bromelain (BRM) is a mixture of proteolytic enzymes found in several parts of the pineapple (Ananas comosus) plant. BRM is widely administered for its well-recognized properties, mainly anti-inflammatory, antithrombotic and fibrinolytic, anticancer, and immunomodulatory. BRM gained universal acceptance as a phytotherapeutic agent due to its extensive dietary usage and lack of side effects; however, the complete molecular mechanism of action of BRM has not been completely identified. This exploratory study focuses on the erectile responses of human cavernosal strips on isometric tension measurements. In this study, we aimed to evaluate the effectiveness of (a) pure BRM (from pineapple stem, Sigma-Aldrich, St Louis, MO), (b) BRM dietary supplement (BG, Natural Brand Bromelain 500mg tablet, GNC, Pittsburgh, PA) and (c) fresh pineapple juice (PAJ) on human corpus cavernosum (HCC). METHODS: HCC tissues were obtained from men undergoing penile prosthesis implantation (n =8-10) and prepared for organ bath experiments as per our published procedures. BRM-induced relaxation response (10-8-10-3 M) was performed in vitro using HCC strips in an organ bath. The effects of inhibitors [NG-nitro-L-arginine methyl ester (L-NAME, 100µM), 1H-[1,2,4]-oxadiazolole-[4,3-a] quinoxalin-10one (ODQ, 30µM), and tetraethylammonium (TEA, 100 µM, blocker Ca2+ - activated K+channels)] on BRM-mediated relaxation responses were evaluated. The relaxation effects of BRM, BG, and PAJ on phenylephrine (Phe)-induced contraction were also compared. The protein expression of endothelial (e) and neuronal (n) nitric oxide synthase (NOS) and vascular endothelium growh factor (VEGF) were determined using Western blotting and immunohistochemistry. RESULTS: BRM inhibited Phe-evoked contractions in a dose-dependent manner. All agents induced relaxation of HCC (maximum response: BRM- 62.87 ± 6.23%, BG - 61.95 ± 4.17%, PAJ -55.68 ± 5.52%) after Phe-contraction. Inhibitors of nitric oxide (L-NAME) and soluble guanylate cyclase (ODQ) as well as TEA failed to affect the BRM-induced HCC relaxations. The relaxant responses of HCC strips were observed in the presence or the absence of BRM products. Furthermore, eNOS and nNOS protein levels were decreased and were not restored after BRM, while VEGF levels remained unaltered. CONCLUSIONS: These data suggest that BRM have the capacity to exert in vitro penile relaxations. The underlying mechanism of BRM is likely independent of the nitric oxide-cyclic guanosine monophosphate pathway. Overall, these in vitro studies suggested that consumption of BRM and its supplements may represent a novel strategy to prevent and treat erectile dysfunction in men, especially due to inflammatory issues. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e364 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Serap Gur More articles by this author Suresh C. Sikka More articles by this author Asim B. Abdel-Mageed More articles by this author Didem Yilmaz-Oral More articles by this author Sudha Talwar More articles by this author Wayne J.G. Hellstrom More articles by this author Expand All Advertisement PDF downloadLoading ...

7-Hydroxycoumarin Induces Vasorelaxation in Animals with Essential Hypertension: Focus on Potassium Channels and Intracellular Ca2+ Mobilization.

Cardiovascular diseases (CVD) are the deadliest noncommunicable disease worldwide. Hypertension is the most prevalent risk factor for the development of CVD. Although there is a wide range of antihypertensive drugs, there still remains a lack of blood pressure control options for hypertensive patients. Additionally, natural products remain crucial to the design of new drugs. The natural product 7-hydroxycoumarin (7-HC) exhibits pharmacological properties linked to antihypertensive mechanisms of action. This study aimed to evaluate the vascular effects of 7-HC in an experimental model of essential hypertension. The isometric tension measurements assessed the relaxant effect induced by 7-HC (0.001 μM-300 μM) in superior mesenteric arteries isolated from hypertensive rats (SHR, 200-300 g). Our results suggest that the relaxant effect induced by 7-HC rely on K+-channels (KATP, BKCa, and, to a lesser extent, Kv) activation and also on Ca2+ influx from sarcolemma and sarcoplasmic reticulum mobilization (inositol 1,4,5-triphosphate (IP3) and ryanodine receptors). Moreover, 7-HC diminishes the mesenteric artery's responsiveness to α1-adrenergic agonist challenge and improves the actions of the muscarinic agonist and NO donor. The present work demonstrated that the relaxant mechanism of 7-HC in SHR involves endothelium-independent vasorelaxant factors. Additionally, 7-HC reduced vasoconstriction of the sympathetic agonist while improving vascular endothelium-dependent and independent relaxation.

Effect of High Testosterone Levels on Endothelial Function in Aorta and Erectile Function in Rats.

BackgroundTestosterone is an important hormone for the physical and mental health of men; however testosterone administration has also been suggested to adversely affect the cardiovascular system.AimTo investigate the effects of excessive testosterone administration on vascular endothelial and erectile function in rats.MethodsA total of seventy-five 12-week-old rats were divided into the following groups: Sham, castrated (Cast), castrated with subcutaneous administration of 100 mg/kg/month testosterone (Cast + T1), and castrated with subcutaneous administration of 100 mg/kg/week testosterone (Cast + T4). To observe the changes in testosterone level after the administration, rats were further divided into the following groups: control; T(6.25), wherein the rats were subcutaneously injected with 6.25 mg/kg testosterone; T(25) per week, wherein the rats were subcutaneously injected with 25 mg/kg testosterone per week; and T(100), wherein the rats were subcutaneously injected with 100 mg/kg testosterone per week. The relaxation responses of aorta were measured in these rats using standardized methods, and their erectile function was also evaluated. Statistical analysis of the obtained data was performed using two-way analysis of variance (ANOVA), Tukey-Kramer's multiple comparison test, or Student's t-test.OutcomesAt the end of the study period, endothelial function was evaluated through measurement of isometric tension, while erectile function was assessed using intracavernosal pressure (ICP), mean arterial pressure (MAP), and the expression of endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), sirtuin 1 (Sirt1) and vascular endothelial growth factor A.ResultsThe ICP/MAP ratio in the Cast group (0.42 ± 0.04) was significantly lower than that in the Sham group (0.79 ± 0.07). The ICP/MAP ratio in the Cast + T1 group (0.73 ± 0.06) was significantly higher than that in the Cast group (P < .01) and that of the Cast + T4 (0.38 ± 0.01) group was unchanged (P > .05). The T(25) and T(100) groups exhibited significantly lower responses to ACh than the control group at 4 weeks (P < .01). Meanwhile, the ICP/MAP ratios in the T(25) group (0.44 ± 0.07) and T(100) group (0.47 ± 0.03) were significantly lower than that in the control group (0.67 ± 0.05) at stimulation frequencies of 16 Hz (P < .05). The expression of androgen receptor, Sirt1, and eNOS were significantly lower while that of iNOS was higher in the T(25) group compared with the control group (P < .05).Clinical TranslationThe results based on this animal model indicate that extremely high testosterone levels may affect endothelial and erectile function.Strengths and LimitationsWe found that high-dose testosterone administration decreased endothelial function in aorta and erectile function in rats. A major limitation of this study is that the blood concentration may not be representative of that in humans, and further research is needed.ConclusionThe findings suggest that high doses of testosterone may cause endothelial dysfunction in the aorta and erectile dysfunction in rats and that the blood concentration should be monitored after testosterone administration.Kataoka T, Fukamoto A, Hotta Y, et al. Effect of High Testosterone Levels on Endothelial Function in Aorta and Erectile Function in Rats. Sex Med 2022;10:100550.

Artemisinin and Its Derivate Alleviate Pulmonary Hypertension and Vasoconstriction in Rodent Models.

Background Pulmonary arterial hypertension (PAH) is a complex pulmonary vasculature disease characterized by progressive obliteration of small pulmonary arteries and persistent increase in pulmonary vascular resistance, resulting in right heart failure and death if left untreated. Artemisinin (ARS) and its derivatives, which are common antimalarial drugs, have been found to possess a broad range of biological effects. Here, we sought to determine the therapeutic benefit and mechanism of ARS and its derivatives treatment in experimental pulmonary hypertension (PH) models. Methods Isolated perfused/ventilated lung and isometric tension measurements in arteries were performed to test pulmonary vasoconstriction and relaxation. Monocrotaline (MCT) and hypoxia+Su5416 (SuHx) were administered to rats to induce severe PH. Evaluation methods of ARS treatment and its derivatives in animal models include echocardiography, hemodynamics measurement, and histological staining. In vitro, the effect of these drugs on proliferation, viability, and hypoxia-inducible factor 1α (HIF1α) was examined in human pulmonary arterial smooth muscle cells (hPASMCs). Results ARS treatment attenuated pulmonary vasoconstriction induced by high K+ solution or alveolar hypoxia, decreased pulmonary artery (PA) basal vascular tension, improved acetylcholine- (ACh-) induced endothelial-dependent relaxation, increased endothelial nitric oxide (NO) synthase (eNOS) activity and NO levels, and decreased levels of NAD(P)H oxidase subunits (NOX2 and NOX4) expression, NAD(P)H oxidase activity, and reactive oxygen species (ROS) levels of pulmonary arteries (PAs) in MCT-PH rats. NOS inhibitor, L-NAME, abrogated the effects of ARS on PA constriction and relaxation. Furthermore, chronic application of both ARS and its derivative dihydroartemisinin (DHA) attenuated right ventricular systolic pressure (RVSP), Fulton index (right ventricular hypertrophy), and vascular remodeling of PAs in the two rat PH models. In addition, DHA inhibited proliferation and migration of hypoxia-induced PASMCs. Conclusions In conclusion, these results indicate that treatment with ARS or DHA can inhibit PA vasoconstriction, PASMC proliferation and migration, and vascular remodeling, as well as improve PA endothelium-dependent relaxation, and eventually attenuate the development and progression of PH. These effects might be achieved by decreasing NAD(P)H oxidase generated ROS production and increasing eNOS activation to release NO in PAs. ARS and its derivatives might have the potential to be novel drugs for the treatment of PH.

Artificial sweeteners sucralose and acesulfame potassium: A bittersweet story for the cardiovascular system?

Artificial sweeteners (AS) are well known to activate two categories of receptors; sweet taste receptor with high affinity and bitter taste receptors with low affinity. Interestingly, recent data from our and other groups suggested that these two receptors families are expressed throughout the arterial tree. Therefore, it could be interesting to explore if AS may have an impact on vascular function, and to decipher the role of these taste receptors. The aims of this ongoing work is to investigate whether AS, like sucralose and acesulfame potassium (AceK) (1) exhibit vasomotor effect and (2) in that case determine the underlying mechanisms. Biomolecular and functional investigations have been performed on isolated rodent aortas, human dermal micro-arteries and omental arteries. Ex vivo vasomotor function was assessed using isometric tension measurements in organ bath systems. We first confirmed that both endothelial and smooth muscle cells from rodent and human arteries express the transcripts encoding for TAS1R2 and TAS1R3; the heterodimer receptor known to be responsible for the sweet taste. Our ex vivo data showed that only high concentrations (about 10 mM) of AceK and sucralose induce vasomotor responses. While AceK exhibited a vasoconstrictive effect, sucralose induced vasorelaxation. Both responses were found to be independent of the endothelium. Pharmacological inhibition (gurmarin and lactisol) and the use of a TAS1R3 KO mice model demonstrated that AS vasomotor effects do not rely on the sweet taste receptors. In contrast, inhibition of TAS2Rs abolished all responses suggesting that bitter taste receptors are more likely responsible for the AS-induced vascular effects. Additionally, our last observations show that the vasoconstrictive effect of AceK is mediated by RhoA/ROCK pathway. These evidences support the idea that AS can alter vasomotor signaling in the smooth muscle cells. These acute effects are probably mediated by the bitter taste receptor family. Their activation at the vascular level as well as the underlying pathways remains poorly understood, and the physiopathological consequences need to be further investigated.

AICAR promotes endothelium-independent vasorelaxation by activating AMP-activated protein kinase via increased ZMP and decreased ATP/ADP ratio in aortic smooth muscle.

AICAR, an adenosine analog, has been shown to exhibit vascular protective effects through activation of AMP-activated protein kinase (AMPK). However, it remains unclear as to whether adenosine kinase-mediated ZMP formation or adenosine receptor activation contributes to AICAR-mediated AMPK activation and/or vasorelaxant response in vascular smooth muscle. In the present study using endothelium-denuded rat aortic ring preparations, isometric tension measurements revealed that exposure to 1mM AICAR for 30min resulted in inhibition of phenylephrine (1μM)-induced smooth muscle contractility by ∼35%. Importantly, this vasorelaxant response by AICAR was prevented after pretreatment of aortic rings with an AMPK inhibitor (compound C, 40µM) and adenosine kinase inhibitor (5-iodotubercidin, 1µM), but not with an adenosine receptor blocker (8-sulfophenyltheophylline, 100µM). Immunoblot analysis of respective aortic tissues showed that AMPK activation seen during vasorelaxant response by AICAR was abolished by compound C and 5-iodotubercidin, but not by 8-sulfophenyltheophylline, suggesting ZMP involvement in AMPK activation. Furthermore, LC-MS/MS MRM analysis revealed that exposure of aortic smooth muscle cells to 1mM AICAR for 30min enhanced ZMP level to 2014.9±179.4picomoles/mg protein (vs. control value of 8.5±0.6; p<0.01), which was accompanied by a significant decrease in ATP/ADP ratio (1.08±0.02 vs. 2.08±0.06; p<0.01). Together, the present findings demonstrate that AICAR-mediated ZMP elevation and the resultant AMPK activation in vascular smooth muscle contribute to vasorelaxation.

Testosterone improved the erectile dysfunction induced by anti-cancer agent doxolubicine in rats

ABSTRACT Introduction Many chemotherapeutic agents are administered to cancer patients worldwide. We previously reported at the world meeting on Sexual Medicine 2018 that doxorubicin (DOX) increased the risk of erectile dysfunction (ED) according to our analyses of the US Food and Drug Administration (FDA) Adverse Event Reporting System (AERS) database. We also reported that DOX decreased erectile function in a study using rats. DOX also decreased rat testosterone levels. These studies suggest a need for a new treatment method for ED associated with anticancer drug treatment. Objective To investigate the effect of testosterone administration on DOX-induced ED in rats. Methods Twelve-week-old male Wistar ST rats were separated into Control, DOX, and DOX+T groups. DOX (3 mg/kg) was intravenously administered on days 1, 8, 15, and 22 in the DOX and DOX+T groups. Testosterone undecanoate (25 mg/kg) was administered to DOX+T rats on day 1. Erectile function was tested using ICP measurements, and endothelial function was tested by assessing isometric tension. Oxidative stress (NADPH oxidase), inflammation (IL-6), and smooth muscle factor (α-SMA, Cavin-1, and Cavin-2) mRNA expression levels were tested using real-time PCR. Results After the 4-week observation period, the ICP/MAP ratio in the DOX group (0.32 ± 0.03) was significantly decreased compared to the Control group (0.72 ± 0.05) (P &amp;lt;0.01). The ICP/MAP ratio in the DOX + T group (0.61 ± 0.07) was increased significantly compared to the DOX group (P &amp;lt;0.01). According to isometric tension measurements, reactivity to acetylcholine was significantly lower in the DOX group (35.0 ± 5.1%) than in the control group (77.6 ± 7.9%), whereas reactivity in the DOX + T group (69.8 ± 8.5%) was significantly improved (P &amp;lt;0.05). NADPH oxidase-1 and IL-6 mRNA levels were increased in the DOX group compared to the Control group (P &amp;lt;0.01), and levels were decreased relative to the DOX group in the DOX+T group. α-SMA, Cavin-1, and Cavin-2 mRNA levels were decreased in the DOX group compered to the Control group. These levels were improved in the DOX+T group. Conclusions We have demonstrated in rats that androgen replacement therapy may mitigate ED induced by DOX administration. We hypothesize that administration of testosterone improves smooth muscle function and vascular endothelial cell function by suppressing oxidative stress and inflammatory response in the corpus cavernosum, and maintaining normal levels of caveolin-related factors. When androgen deficiency symptoms are observed due to administration of anticancer drugs such as DOX, androgen replacement therapy is expected to be one viable treatment option. Our study sheds light on possible treatment strategies for improving quality of life for cancer survivors. Disclosure Work supported by industry: no.

Sarco/Endoplasmic Reticulum Ca2+ ATPase 2 Activator Ameliorates Endothelial Dysfunction; Insulin Resistance in Diabetic Mice.

Background: Sarco/endoplasmic reticulum Ca2+-ATPase2 (SERCA2) is impaired in various organs in animal models of diabetes. The purpose of this study was to test the effects of an allosteric SERCA2 activator (CDN1163) on glucose intolerance, hepatosteatosis, skeletal muscle function, and endothelial dysfunction in diabetic (db/db) mice. Methods: Either CDN1163 or vehicle was injected intraperitoneally into 16-week-old male control and db/db mice for 5 consecutive days. Results: SERCA2 protein expression was decreased in the aorta of db/db mice. In isometric tension measurements of aortic rings from db/db mice treated with CDN1163, acetylcholine (ACh)-induced relaxation was improved. In vivo intraperitoneal administrations of CDN 1163 also increased ACh-induced relaxation. Moreover, CDN1163 significantly decreased blood glucose in db/db mice at 60 and 120 min during a glucose tolerance test; it also decreased serum insulin levels, hepatosteatosis, and oxygen consumption in skeletal muscle during the early period of exercise in db/db mice. Conclusions: CDN1163 directly improved aortic endothelial dysfunction in db/db mice. Moreover, CDN1163 improved hepatosteatosis, skeletal muscle function, and insulin resistance in db/db mice. The activation of SERCA2 might be a strategy for the all the tissue expressed SERCA2a improvement of endothelial dysfunction and the target for the organs related to insulin resistance.

Smooth muscle Rac1 contributes to pulmonary hypertension.

Background and PurposePulmonary hypertension (PH) is a multifactorial chronic disease characterized by an increase in pulmonary artery (PA) resistance leading to right ventricle (RV) failure. Endothelial dysfunction and alteration of NO/cGMP signalling in PA plays a major role in PH. We recently described the involvement of the Rho protein Rac1 in the control of systemic blood pressure through its involvement in NO‐mediated relaxation of arterial smooth muscle cell (SMC). The aim of this study was to analyse the role of SMC Rac1 in PH.Experimental ApproachPH is induced by exposure of control and SMC Rac1‐deficient (SM‐Rac1‐KO) mice to chronic hypoxia (10% O2, 4 weeks). PH is assessed by the measurement of RV systolic pressure and hypertrophy. PA reactivity is analysed by isometric tension measurements. PA remodelling is quantified by immunofluorescence in lung sections and ROS are detected using the dihydroethidium probe and electronic paramagnetic resonance analysis. Rac1 activity is determined by immunofluorescence.Key ResultsRac1 activation in PA of hypoxic mice and patients with idiopathic PH. Hypoxia‐induced rise in RV systolic pressure, RV hypertrophy and loss of endothelium‐dependent relaxation were significantly decreased in SM‐Rac1‐KO mice compared to control mice. SMC Rac1 deletion also limited hypoxia‐induced PA remodelling and ROS production in pulmonary artery smooth muscle cells (PASMCs).Conclusion and ImplicationsOur results provide evidence for a protective effect of SM Rac1 deletion against hypoxic PH. Rac1 activity in PASMCs plays a causal role in PH by favouring ROS‐dependent PA remodelling and endothelial dysfunction induced by chronic hypoxia.

Vasorelaxant and anti-proliferative effects of lefluomide

Leflunomide (LEF) is a immunomodulator indicated in various diseases including rheumatoid arthritis. Recently, a link between this drug and pulmonary arterial hypertension (PAH) has been suggested (Lacoste Palasset et al., 2021, Ann Am Thorac Soc). Our aim was to examine the effect of LEF on pulmonary artery (PA) tone, whose abnormality is associated with PAH. Distal intralobar PAs and mesenteric arteries (MA) were isolated from male Wistar rats. PA were also collected from subjects with lung cancer, distal from tumor areas. PAs segments were mounted on a myograph for measurement of isometric tension and stimulated with various contractile agents and inhibitors. Experiments were conducted in the presence of LEF, its metabolite teriflunomide (TER) or vehicle (DMSO) (<0.7%). LEF (100 μM) dramatically inhibited the contractile response to high K + , phenylephrine (PE) and U46619 in rat PAs. LEF decreased E max of PE by 77% and induced a 3-fold increase in EC 50 compared to vehicle. Similar effects were observed in MA. Effect of LEF was unaffected by endothelium removal and was relieved after LEF wash out. Concentrations >10 μM of LEF produced a dose-dependent relaxation of PAs precontracted with U46619. TER had intermediary effect on K + response in PA and MA. TER exerted similar inhibition as LEF on PE-evoked contraction in MA, but had a milder effect in PA. In the latter, TER decreased E max by 42% and did not change EC 50 of PE. With calcium-free solution or nifedipine LEF still inhibited response to PE, suggesting the effect is not caused by Ca 2+ influx inhibition. Preliminary data showed that LEF inhibited contractile responses to K + and PE in human PAs, but surprisingly had no effect on U46619 response. Concentrations ≥100 μM inhibit proliferation of human pulmonary arterial smooth muscle cells(hPASMCs) LEF evoked a robust inhibitory effect of rat and human vascular tone at high, yet clinically relevant concentrations. Experiments are currently ongoing in order to clarify the actual mechanism.

Attenuation of Aging-Induced Vascular Dysfunction by Inhibition of Ca2+/Calmodulin Protein Kinase II (CaMKII) in Isolated Renal and Carotid Rat Arteries

An increased prevalence of cardiovascular problems is recorded due to aging. The importance of aging as a potential risk factor for cardiovascular diseases has been increasing in most of the developing countries since populations continue to become older. Age-associated unusual structural changes that develop in blood vessels have been reported such as stiffening of the vasculature and fibrosis. CaMKII is a protein kinase that is present all-over in the body. In this study, it is suggested that acute inhibition of CaMKII-mediated signaling may be an effective method to prevent agingassociated detrimental changes in isolated blood vessels in SD male rats. The inhibitory effect of CaMKII in aging-induced renal/carotid vascular dysfunction was studied using the selective inhibitor KN-93. Isolated ring segments of the renal or carotid arteries were suspended in organ-bath chambers for measurement of isometric tension. Responses to Phenylephrine (PE), Endothelin-1 (ET-1), carbachol and Sodium Nitroprusside (SNP) were determined by measurement of changes in isometric tension. Results from this study showed abnormal vascular responses to vasoactive agonists in the vessels obtained from aged rats. Vasoconstrictor responses to phenylephrine were potentiated, while vasodilator responses to carbachol were reduced in blood vessels obtained from aged rats, in comparison to responses in young rats. Acute incubation of the blood vessels with KN-93 (10-5 M), an inhibitor of CaMKII, resulted in significant improvement in vascular function to both vasoactive agonists. Our results indicated that activation of CaMKII pathway contributes to aging-induced vascular dysfunction. Therefore, development of novel therapies that inhibit CaMKII pathway may prevent or reduce development of vascular abnormalities induced by aging.

Evaluating aminophylline and progesterone combination treatment to modulate contractility and labor-related proteins in pregnant human myometrial tissues.

Progesterone (P4) and cyclic adenosine monophosphate (cAMP) are regarded as pro‐quiescent factors that suppress uterine contractions during pregnancy. We previously used human primary cells in vitro and mice in vivo to demonstrate that simultaneously enhancing myometrial P4 and cAMP levels may reduce inflammation‐associated preterm labor. Here, we assessed whether aminophylline (Ami; phosphodiesterase inhibitor) and P4 can reduce myometrial contractility and contraction‐associated proteins (CAPs) better together than individually; both agents are clinically used drugs. Myometrial tissues from pregnant non‐laboring women were treated ex vivo with Ami acutely (while spontaneous contracting) or throughout 24‐h tissue culture (±P4); isometric tension measurements, PKA assays, and Western blotting were used to assess tissue contractility, cAMP action, and inflammation. Acute (1 h) treatment with 250 and 750 μM Ami reduced contractions by 50% and 84%, respectively, which was not associated with a directly proportional increase in whole tissue PKA activity. Sustained myometrial relaxation was observed during 24‐h tissue culture with 750 μM Ami, which did not require P4 nor reduce CAPs. COX‐2 protein can be reduced by 300 nM P4 but this did not equate to myometrial relaxation. Ami (250 μM) and P4 (100 and 300 nM) co‐treatment did not prevent oxytocin‐augmented contractions nor reduce CAPs during interleukin‐1β stimulation. Overall, Ami and P4 co‐treatment did not suppress myometrial contractions more than either agent alone, which may be attributed to low specificity and efficacy of Ami; cAMP and P4 action at in utero neighboring reproductive tissues during pregnancy should also be considered.

ATT has positive effects on pulmonary hypertension hallmarks

Pulmonary hypertension (PH) is a multifactorial disease characterized by pulmonary arteries (PA) hyperreactivity and remodelling involving an imbalance of contractile and proliferative agents such as 5-hydroxytryptamine (5-HT). Mitochondria and associated reactive oxygen species (ROS) production were shown to contribute to these phenomena. OP2 Drugs recently demonstrated that Anethole Trithione (ATT), the active ingredient of its principal lead OP2113, specifically inhibits mitochondrial ROS (mtROS) production from complex I in its reverse mode. In this context, this study aims to assess the effects of ATT on PH hallmarks. Male rats were either exposed to normoxia or chronic hypoxia (10% O2) during 3 weeks to induce PH (CH-PH). The effect of ATT on PA reactivity was determined ex vivo by isometric tension measurements of arterial rings. PA contraction was induced by 5-HT, prostaglandin F2α (PGF2α), phenylephrine (Phe) or endothelin-1 (ET-1) whereas relaxation was induced by carbachol (Cch) on preconstricted vessels with PGF2α. The effect of ATT on calcium responses induced by 5-HT was assessed in rat PA smooth muscle cells using confocal imaging. Proliferative responses induced by 5-HT were evaluated by ELISA BrdU on human PASMC in presence or absence of ATT. In rats with CH-PH, ATT reduced contractile hyperreactivity induced by 5-HT and PGF2α. In control rats, ATT treatment also decreased contraction to 5-HT and Phe, but not contraction to ET-1 and PGF2α as well as relaxation to Cch. Interestingly, acute ATT exposure did not modify basal cytosolic calcium signal in control rat PASMC. However, the number of 5-HT responding cells was reduced in presence of ATT whereas neither maximal peak of cytosolic calcium responses nor the global calcium variations were affected. Finally, 5-HT-induced proliferation was reduced by ATT in control human PASMC. In conclusion, ATT improves vascular hyperreactivity of PA from rats with CH-PH whereas in control condition ATT altered 5-HT-induced contraction in rat PA, calcium signalling to 5-HT in rat PASMC and 5-HT-induced human PASMC proliferation. Although mechanisms underlying ATT influence on PH hallmarks need to be further elucidated, these Results suggest that OP2113 may be used to develop new PH therapies.

Sucralose and Acesulfame K modulate human and rodent vascular smooth muscle contractility independently of the presence of the sweet taste receptor. A study of the SOSweet project

Originally thought to be physiologically inert, artificial sweeteners are more and more recognized to alter various biological functions through their interaction with the sweet taste receptor in extraoral sites. Alarmingly, recent epidemiological data have shown that frequent consumption of artificial sweeteners (AS) is associated with an increased risk of vascular events. However, to date, no studies have tested the hypothesis that AS might directly impact the vasculature. The aim is to characterize the effect of the highly consumed AS, Sucralose and Acesulfame K (AceK), on the vascular wall. The specific objective of the present study is to focus on the vasomotor function. Biomolecular and functional investigations were performed on isolated rodent aortas, human dermal micro-arteries and omental arteries. Ex-vivo vasomotor function was assessed using isometric tension measurements in an organ bath system. Our preliminary data show that mRNA of both T1R2 and T1R3, the two subunits of the sweet taste receptor, are expressed in the vascular wall. Cumulative addition of AceK or sucralose revealed that high concentration (10 mM) of these molecules exert respectively vasoconstrictive and vasorelaxant properties on both rodent and human arteries. Lower concentrations (1 mM) of AceK were associated with an exacerbated vasoreactivity to the α1 adrenergic agonist phenylephrine. All these effects were independent of the presence of the endothelium. Surprisingly, T1R inhibition with gurmarin, as well as T1R3 invalidation (KO mice), had no consequence on sucralose and AceK vasoactive effects. Our work first show that AS can modulate smooth muscle vascular tone. The in-vivo significance and molecular mechanisms involved remain to be determined. Future investigations will also address other vascular functions to better understand the possible consequences of AS consumption on the cardiovascular system.