KCl-induced Contraction Research Articles

Abstract P448: Follistatin Improves Vascular Function by Regulating Perivascular Adipose Tissue in Essential Hypertension

Introduction: Essential hypertension is characterized by resistance artery remodeling induced by oxidative stress. Most vessels are surrounded by perivascular adipose tissue (PVAT) which regulates vascular tone via release of vasoactive substances. In physiological conditions, PVAT induces an anticontractile effect. In pathological conditions such as hypertension, PVAT exhibit increased oxidative stress resulting in augmented contraction and reduced relaxation. Follistatin, an antioxidant glycoprotein, has been shown to induce adipose tissue browning which is linked to improved vasorelaxation and BP. We hypothesize that follistatin, through ROS inhibition and PVAT browning, lowers BP and improves vessel function in a model of essential hypertension. Methods: Spontaneously hypertensive rats (SHR) were treated with vehicle or follistatin every other day for 8 weeks. Wistar Kyoto (WKY) rats served as normotensive controls. BP was measured weekly by radiotelemetry. Mesenteric arteries and PVAT were used. KCl-induced smooth muscle contraction was assessed using wire myography. ROS was measured by DHE (dihydroethidium) staining. Vasodilator nitric oxide (NO) bioavailability in PVAT was measured using DAF-2 FM. Protein expression of markers for ROS or PVAT browning was measured by immunohistochemistry. Results: Follistatin significantly lowered BP in SHRs and restored anticontractile effect of PVAT. Increased ROS in SHR vessels and PVAT were also inhibited. Follistatin inhibited SHR PVAT-induced vascular oxidative stress. SHR PVAT NO bioavailability was increased by acute follistatin treatment via ROS inhibition. Follistatin also increased expression of brown adipose tissue markers in SHR PVAT suggesting PVAT browning. Limitations: Above studies do not confirm whether PVAT pathology causes hypertension in this model. Vascular dysfunction is an independent risk factor for CVD and our studies do not yet consider effects of follistatin on end-organ damage. Conclusions: Follistatin lowers BP in SHRs likely via improved vascular and perivascular structure and function. Specifically, follistatin inhibited perivascular ROS, increased NO and induced PVAT browning suggesting improved regulation of vascular function and thus, BP. Future work will utilize proteomic assays to identify novel mediators of follistatin effects on PVAT in the SHR.

Phytochemical profile and pharmacological potential of Withania somnifera whole plant extracts.

Withania somnifera belongs to the family Solanaceae, commonly called ashwagandha, and is traditionally used as an astringent, hepatoprotective and antioxidant, and as a treatment for rheumatism. Therefore the current study aimed to explore the dichloromethane fraction of W. somnifera whole plant (DCFWS) and ethyl acetate fraction of W. somnifera (EAFWS) using gas chromatoghraphy-mass spectrometry (GC-MS) analysis and to find the acetylcholinesterase inhibition potential along with spasmolytic activity. The GC-MS-detected phytochemicals were 2,4-bis(1,1-dimethylethyl), hexadecanoic acid, 1-nonadecene and 11-octadecenoic acid. The DCFWS and EAFWS exhibited acetylcholinesterase inhibitory potential with significant inhibitory concentration values. The acute toxicity results of both fractions showed high toxicity, causing emesis at 0.5g and both emesis and diarrhea at 1g/kg. Both fractions exhibited significant (p ≤ 0.01) laxative activity against metronidazole (7mg/kg) and loperamide hydrochloride (4mg/kg) induced constipation. Both DCFWS (66.8 ± 3.85%) and EAFWS (58.58 ± 3.28%) significantly (p ≤ 0.05) increased charcoal movement compared with distal water (43.93 ± 4.34%). Similarly the effect of DCFWS on KCl-induced (80 mm) contraction was more significant as compared with EAFWS. It was concluded that the plant can be used in the treatment of gastrointestinal tract diseases such as constipation. Furthermore, additional work is required in the future to determine the bioactive compounds that act as therapeutic agents in W. somnifera.

Relaxant Effects of Curcuma aeruginosa Rhizome Extracts on Isolated Rat Gastric Fundus and Ileum Contraction

Curcuma aeruginosa (CA) rhizomes are used in traditional medicine as gastrointestinal remedies, postpartum care and uterine issues. However, its effects on gastrointestinal motility have not yet been explored. Extracts of CA rhizomes prepared using chloroform, methanol and water were evaluated for their effects on gastrointestinal contractions using isolated rat gastric fundus and ileum. Varied solvents aim for extraction of different compounds of CA rhizome. In the ileum, the 3 extracts did not significantly affect spontaneous contractions, but significantly reduced contractions induced by acetylcholine (ACh, 0.3 µM) and KCl (40 mM) in a concentration-dependent manner. The order of potency, based on ACh-induced contraction, was chloroform > methanol > water extracts, with respective IC50 values of 0.025 ± 0.001, 0.46 ± 0.02 and 2.57 ± 0.47 mg/mL. Similar potency order against KCl-induced contraction was observed, with IC50 values of 0.011 ± 0.002, 0.47 ± 0.06 and 1.18 ± 0.18 mg/mL, respectively. In the isolated gastric fundus model, both methanol and water extracts resulted in an increase in the force of contraction in the absence of stimulation. However, when ACh (0.3 µM) was introduced, the methanol and water extracts exhibited a concentration-dependent reduction in contractions, with IC50 values of 0.62 ± 0.06 and 2.30 ± 0.32 mg/mL, respectively. As for KCl (40 mM)-induced contraction, only the highest concentration of the water extract (3.75 mg/mL) significantly decreased the contraction by 41.29 ± 2.94 %. CA extract demonstrated relaxant effects on both isolated rat gastric fundus and ileal contractions induced by ACh and KCl. These findings support the use of CA in traditional medicine as a gastrointestinal remedy. These extracts have the potential to be used as antispasmodics and to treat infectious and non-infectious diarrhea, the latter of which occurs in functional gastrointestinal diseases. It might also be useful as a gastroprokinetic. HIGHLIGHTS C. aeruginosa extracts had no impact on rat ileum’s spontaneous contraction Extracts caused dose-dependent relaxation of precontracted ileum Extracts enhanced spontaneous contraction of isolated gastric fundus Extracts induced relaxation in the precontracted isolated gastric fundus GRAPHICAL ABSTRACT

Vascular contraction of umbilical arteries of pregnant women with preeclampsia.

Potassium channels have an important role in the vascular adaptation during pregnancy and a reduction in the expression of adenosine triphosphate-sensitive potassium channels (Katp) has been linked to preeclampsia. Activation of Katp induces vasodilation; however, no previous study has been conducted to evaluate the effects of the inhibition of these channels in the contractility of preeclamptic arteries. Glibenclamide is an oral antihyperglycemic agent that inhibits Katp and has been widely used in vascular studies. To investigate the effects of the inhibition of Katp, umbilical arteries of preeclamptic women and women with healthy pregnancies were assessed by vascular contractility experiments, in the presence or absence of glibenclamide. The umbilical arteries were challenged with cumulative concentrations of potassium chloride (KCl) and serotonin. There were no differences between the groups concerning the maternal age and gestational age of the patients. The percentage of smokers, caucasians and primiparae per group was also similar. On the other hand, blood pressure parameters were elevated in the preeclamptic group. In addition, the preeclamptic group presented a significantly higher body mass index. The newborns of both groups presented similar APGAR scores and weights. In the presence of glibenclamide, there was an increase in the KCl-induced contractions only in vessels from the PE group, showing a possible involvement of these channels in the disorder.

Changes in the conflicting nongenomic effects of progesterone in rat myometrium during pregnancy

AimsAlthough the functions of progesterone in the myometrium are well-established, the nongenomic effects of progesterone in pregnant myometrial contractions are still unclear. Therefore, this study aimed to investigate changes in the nongenomic effects of progesterone during pregnancy. Main methodsMyometrial strips were obtained from non-pregnant, pregnant, and postpartum rats, and the nongenomic effects of progesterone in the myometrium during pregnancy were examined. Additionally, the influence of actinomycin D and cycloheximide and the effects of Org OD-02-0 (a specific membrane progesterone receptor (mPR) agonist) in the myometrium were investigated. Moreover, DNA microarray and quantitative real-time polymerase chain reaction (qRT-PCR) were performed to identify genes involved in progesterone-induced effects in the myometrium. Key findingsProgesterone did not cause rhythmic contractions in non-pregnant myometrium but induced rhythmic contractions in pregnant myometrium, with the effects peaking at 20 d + 8 h of pregnancy. However, myometrial contractions decreased after delivery and were restored to non-pregnant levels at 7 d postpartum. Additionally, progesterone stably inhibited high KCl-induced myometrial contractions during pregnancy. Moreover, the nongenomic effects of progesterone were unaffected by actinomycin D or cycloheximide, and Org OD-02-0 effectively mimicked these effects. DNA microarray analysis and qRT-PCR revealed a significant increase in mPRβ gene expression during pregnancy. However, mPRα, mPRγ, mPRδ, and mPRε expression levels remained unchanged. SignificanceThe stimulatory nongenomic effect of progesterone, which was inducible and mPRβ-dependent during pregnancy, may be involved in parturition. The inhibitory effect, which was constitutive and depended on other mPRs, may be involved in pregnancy maintenance.

Relaxant Effects of Piperine and Piperlongumine from Piper longum Fruits on Porcine Coronary Artery.

Since ancient times, Piper longum Linn. fruits have been recognized for exhibiting various effects, including the diaphoretic effects linked to enhanced blood flow. Piperine and piperlongumine coexist in Piper longum Linn. fruits, although the cardiovascular effects of both compounds remain elusive. We investigated their action of piperine and piperlongumine in porcine coronary arteries, comparing them to the Ca2+ channel antagonist diltiazem. Piperlongumine, unlike piperine or diltiazem, concentration-dependently inhibited basal contractile tone in endothelium-denuded coronary arteries. All three compounds inhibit tonic contractions induced by high potassium chloride (KCl) concentrations. The order of relaxation potency indexed by the half-maximal effective concentration (EC50) were as follows: diltiazem > piperlongumine > piperine. These effects were not different between endothelium-intact and -denuded preparations. In endothelial-denuded preparations, pretreatment with these compounds not only inhibited KCl-induced tonic contractions attenuated calcium chloride (CaCl2)-induced ones in a Ca2+-free medium. Histamine-induced phasic contractions in a Ca2+-free medium containing intracellular Ca2+ chelator was completely suppressed by selective inositol trisphosphate receptor antagonist and piperlongumine, whereas piperine or diltiazem do not have the same effect. These findings suggest that piperine and piperlongumine similar to diltiazem cause vasorelaxation by inhibiting both KCl- and CaCl2-induced contractions in coronary arteries, possibly through the inhibition of voltage-dependent Ca2+ channels. Piperlongumine inhibits histamine-induced contractions in a Ca2+-free medium, which is associated with the intracellular Ca2+ signaling pathway, suggesting that the relaxant effect of piperlongumine differs from that of piperine.

Adjuvant-induced arthritis promotes vascular hyporesponsiveness to phenylephrine through a nitric oxide-related mechanism.

Arthritis has important cardiovascular repercussions. Phenylephrine-induced vasoconstriction is impaired in rat aortas in the early phase of the adjuvant-induced arthritis (AIA), around the 15th day post-induction. Therefore, the present study aimed to verify the effects of AIA on hyporesponsiveness to phenylephrine in rat aortas. AIA was induced by intradermal injection of Mycobacterium tuberculosis (3.8 mg/dL) in the right hind paw of male Wistar rats (n=27). Functional experiments in isolated aortas were carried out 15 days after AIA induction. Morphometric and stereological analyses of the aortas were also performed 36 days after the induction of AIA. AIA did not promote structural modifications in the aortas at any of the time points studied. AIA reduced phenylephrine-induced contraction in endothelium-intact aortas, but not in endothelium-denuded aortas. However, AIA did not change KCl-induced contraction in either endothelium-intact or denuded aortas. L-NAME (non-selective NOS inhibitor), 1400W (selective iNOS inhibitor), and ODQ (guanylyl cyclase inhibitor) reversed AIA-induced hyporesponsiveness to phenylephrine in intact aortas. 7-NI (selective nNOS inhibitor) increased the contraction induced by phenylephrine in aortas from AIA rats. In summary, the hyporesponsiveness to phenylephrine induced by AIA was endothelium-dependent and mediated by iNOS-derived NO through activation of the NO-guanylyl cyclase pathway.

Alkaloids from <i>Peganum harmala</i> attenuated contractile responses of vascular smooth muscle cells

Purpose: To investigate the contractile responses of vascular smooth muscle cells (VSMCs) to spasmogens after incubation with harmaline, harmine, and harmalol, which are alkaloids obtained from Peganum harmala L., a member of the Zygophyllaceae family.
 Methods: Contractile responses of VSMCs to norepinephrine (NE; 1 µmol/L) and potassium chloride (KCl; 60 mmol/L) were recorded in rat aortic ring preparations pre-incubated with 0.5, 1, 5 and 10 µmol/L of each alkaloid for 15 min. Responses were expressed as mean values of contractions in incubated preparations, relative to the recorded tension prior to treatment with alkaloids.
 Results: Pre- incubation with harmaline at concentration of 10 µmol/L significantly reduced contractile responses to NE by 69.0 ± 3.0 % (p < 0.00002), and decreased KCl-induced contraction by 34.0 ± 9.0 % (p < 0.05). Harmalol was the most effective in inhibiting contractions to KCl (48.0 ± 9.0 %, p < 0.01). However, harmalol produced relatively moderate inhibitory effects on NE-induced contractions (46.0 ± 4.0 %, p < 0.005), followed by harmine (52.0 ± 8.0 %, p < 0.02), but it did not significantly affect contractile responses to KCl.
 Conclusion: These results highlight the differential effects of pre-incubation with alkaloids from P. harmala and their potential effects on the prevention of VSMC spasms induced by either chemicals or stimuli that change the membrane potential.

Pitavastatin and Lovastatin Exhibit Calcium Channel Blocking Activity Which Potentiate Vasorelaxant Effects of Amlodipine: A New Futuristic Dimension in Statin's Pleiotropy.

Background and Objectives: We have recently reported that Fluvastatin, Atorvastatin, Simvastatin and Rosuvastatin have calcium channel antagonistic activities using rabbits' intestinal preparations. The current study is focused on the effects of Pitavastatin and Lovastatin for possible inhibition of vascular L-Type calcium channels, which may have vasorelaxant effect(s). Combined effects of Pitavastatin and Lovastatin in the presence of Amlodipine were also tested for vasorelaxation. Materials and Methods: Possible relaxing effects of Pitavastatin and Lovastatin on 80 mM Potassium chloride (KCL)-induced contractions and on 1 µM norepinephrine (N.E)-induced contractions were studied in isolated rabbit's aortic strips preparations. Relaxing effects on 80 mM KCL-induced vascular contractions were further verified by constructing Calcium Concentration Response Curves (CCRCs), in the absence and presence of three different concentrations of Pitavastatin and Lovastatin using CCRCs as negative control. Verapamil was used as a standard drug that has L-Type calcium channel binding activity. In other series of experiments, we studied drug interaction(s) among Pitavastatin, Lovastatin, and amlodipine. Results: The results of this study imply that Lovastatin is more potent than Pitavastatin for having comparatively lower EC50 (7.44 × 10-5 ± 0.16 M) in intact and (4.55 × 10-5 ± 0.10 M) in denuded aortae for KCL-induced contractions. Lovastatin amplitudes in intact and denuded aortae for KCL-induced contractions were, respectively, 24% and 35.5%; whereas amplitudes for Pitavastatin in intact and denuded aortae for KCL-induced contractions were 34% and 40%, respectively. A left shift in the EC50 values for the statins was seen when we added amlodipine in EC50 (Log Ca++ M). Right shift for CCRCs state that Pitavastatin and Lovastatin have calcium channel antagonistic effects. Lovastatin in test concentration (6.74 × 10-7 M) produced a right shift in relatively lower EC50 (-2.5 ± 0.10) Log Ca++ M as compared to Pitavastatin, which further confirms that lovastatin is relatively more potent. The right shift in EC50 resembles the right shift of Verapamil. Additive effect of Pitavastatin and Lovastatin was noted in presence of amlodipine (p < 0.05). Conclusions: KCL (80 mM)-induced vascular contractions were relaxed by Pitavastatin and Lovastatin via inhibitory effects on L-Type voltage-gated calcium channels. Lovastatin and Pitavastatin also relaxed Norepinephrine (1 µM)-induced contractions giving an insight for involvement of dual mode of action of Pitavastatin and Lovastatin.

Effects of hydrogen sulfide on relaxation responses in the lower esophageal sphincter in rabbits: the potential role of potassium channels.

Hydrogen sulfide (H2S) is a significant physiologic inhibitory neurotransmitter. The main goal of this research was to examine the contribution of diverse potassium (K+) channels and nitric oxide (NO) in mediating the H2S effect on electrical field stimulation (EFS)-induced neurogenic contractile responses in the lower esophageal sphincter (LES). EFS-induced contractile responses of rabbit isolated LES strips were recorded using force transducers in organ baths that contain Krebs-Henseleit solutions (20ml). Cumulative doses of NaHS, L-cysteine, PAG, and AOAA were evaluated in NO-dependent and NO-independent groups. The experiments were conducted again in the presence of K+ channel blockers. In both NO-dependent and NO-independent groups, NaHS, L-cysteine, PAG, and AOAA significantly reduced EFS-induced contractile responses. In the NO-dependent group, the effect of NaHS and L-cysteine decreased in the presence of 4-AP, and also the effect of NaHS decreased in the NO-dependent and independent group in the presence of TEA. In the NO-independent group, K+ channel blockers didn't change L-cysteine-induced relaxations. K+ channel blockers had no impact on the effects of PAG and AOAA. In addition, NaHS significantly relaxed 80-mM KCl-induced contractions, whereas L-cysteine, PAG, and AOAA did not. In the present study, H2S decreased the amplitudes of EFS-induced contraction responses. These results suggest that Kv channels and NO significantly contribute to exogenous H2S and endogenous H2S precursor L-cysteine inhibitory effect on lower esophageal sphincter smooth muscle.

Abstract P104: EXAMINING THE EFFECTS OF FOLLISTATIN ON CONTRACTION OF VESSELS FROM NORMOTENSIVE AND HYPERTENSIVE RATS

The lab has previously shown that follistatin (FST), a glycoprotein inhibitor of activins, reduced blood pressure in the Spontaneously Hypertensive Rat (SHR) model of Essential Hypertension. Short-term exposure (30 minutes) to FST also reduced vessel contraction induced by potassium (KCl). This study aims to illustrate the mechanisms through which FST inhibits potassium-induced contraction in SHR and normotensive (WKY) rats. Function of SHR or WKY resistance mesenteric arteries was tested in response to KCl and ion channel modulators using wire myography. Cultures of primary smooth muscle cells (SMC) were also established from these vessels using cell explant technique. The calcium sensor dye Fluo-4 AM was used to examine calcium influx on a cellular level. To test whether FST effects were due to activin neutralization or activin-receptor inhibition, neutralizing antibodies against activin A and B or an activin receptor inhibitor (SB 431542) were used, respectively. Only activin A neutralization in the SHR reduced KCl-induced contraction similarly to FST. Activin receptor inhibition also reduced KCl constriction similarly to FST. When directly stimulated with Activin A, both WKY and SHR vessels displayed augmented KCl contraction compared to controls but the effect was more pronounced in the SHR. Preliminary Fluo-4 results showed that FST decreased KCl-induced calcium influx in SMC. Since activin A was shown to increase L-type voltage-gated Ca2+channel activity, an agonist (FPL 64176) of this channel was used to induce contraction. Although FST reduced KCl-induced contraction, it did not affect FPL-induced contraction in either SHR or WKY. Thus, Activin A neutralization reproduces FST reduction of KCl-induced vessel contraction. FST did not reduce FPL-induced contraction, suggesting that its inhibition of KCl-induced contraction is not through effects on this channel but rather an alternate Ca2+ or K-ATP channel.

Pharmacological study on the enhancing effects of U46619 on guinea pig urinary bladder smooth muscle contraction induced by acetylcholine and α,β-methylene ATP and the possible involvement of protein kinase C

We examined whether U46619 (a prostanoid TP receptor agonist) could enhance the contractions of guinea pig urinary bladder smooth muscle (UBSM) in response to acetylcholine (ACh) and an ATP analog (α,β-methylene ATP (αβ-MeATP)) through stimulation of the UBSM TP receptor and whether protein kinase C (PKC) is involved. U46619 (10−7 M) markedly enhanced UBSM contractions induced by electrical field stimulation and ACh/αβ-MeATP (3 × 10−6 M each), the potentiation of which was completely suppressed by SQ 29,548 (a TP receptor antagonist, 6 × 10−7 M). PKC inhibitors did not attenuate the ACh-induced contractions enhanced by U46619 although they partly suppressed the U46619-enhanced, αβ-MeATP-induced contractions. While phorbol 12-myristate 13-acetate (PMA, a PKC activator, 10−6 M) did not enhance ACh-induced contractions, it enhanced αβ-MeATP-induced contractions, an effect that was completely suppressed by PKC inhibitors. αβ-MeATP-induced contractions, both with and without U46619 enhancement, were strongly inhibited by diltiazem. U46619/PMA enhanced 50 mM KCl-induced contractions, the potentiation of which was partly/completely attenuated by PKC inhibitors. These findings suggest that U46619 potentiates parasympathetic nerve-associated UBSM contractions by stimulating UBSM TP receptors. PKC-increased Ca2+ influx through voltage-dependent Ca2+ channels may partially play a role in purinergic receptor-mediated UBSM contractions enhanced by TP receptor stimulation.

Vasorelaxant Properties of Moringa oleiferaleaf extract: An in-vitro study on mice blood vessels

Background: Moringa oleifera is a plant rich in bioactive compounds, including flavonoids, polyphenols, and alkaloids, which have been shown to have numerous health benefits. In recent years, several studies have investigated the potential of Moringa oleifera in the treatment ofhypertension and diseases of vascular dysfunction. Aim: To observe the effect of M. oleifera leaf extract on contractility of aortic tissue of mice, in vitro. Methods: An animal-based in-vitro experimental study was carried out in Pharmacology Department of CMH Lahore Medical College and Institute of Dentistry from February 2022 to March 2023. Mice were euthanized with ketamine. Aortic tissue was dissected and mounted in the organ bath. For evaluation of vasodilatory effect, cumulative dose-response curve of M. oleifera leaf extract was obtained using increasing doses of the extract against1 µM adrenaline and 80 mM KCl, in group I and group II, respectively.Response was obtained through Powe rLab (AD Instruments, Australia). Results: A consistent decrease was recorded against adrenaline and KCl-induced contractions in aorta, resulting in vasodilation. IC50 was 0.068 mg and 0.161 mg, in group I and II, respectively. Difference between IC50 of both groups was statistically significant (p-value = 0.0008). Conclusion: Leaf extract of Moringa oleifera exerts smooth muscle relaxant effectin blood vessels, most likely through inhibition of calcium influx, mediated through Gq-signalling pathway as well as depolarization-dependent voltage operated calcium channels. Keywords: Moringa oleifera, dose-response relationship, trachea, aorta, calcium channels

Effects of the thromboxane receptor antagonist S18886 in the porcine coronary circulation

Thromboxane A2 (TxA 2 ) is a potent coronary vasoconstrictor that has been implicated in promoting decreases in myocardial perfusion in a variety of (patho)-physiologic conditions. S18886 is a promising orally-active TxA 2 receptor antagonist currently approved for investigational clinical use. However, the coronary vascular effects of S18886 are unknown and its specificity and affinity for the thromboxane receptor in the coronary circulation remain unclear. We tested the hypothesis that administration of S18886 dose-dependently attenuates coronary vasoconstriction to the TxA 2 mimetic U46619 without influencing coronary responses to prostaglandin F 2α , acetylcholine, or smooth muscle depolarization (K + ). Experiments to test this hypothesis were performed in male (n = 5) and female (n = 6) domestic swine. Hearts were excised and the left circumflex coronary artery isolated, cleaned of periadventitial fat, and cut into 3 mm rings. Isometric tension of coronary artery rings was measured in response to log order increments of U46619 (1 nM to 1 μM) with and without S18886 (0.1-100 nM). Similar isometric studies were conducted with prostaglandin F 2α (10 nM-10 μM), acetylcholine (0.1-10 μM), and KCl (5-90 mM). U46619 induced concentration dependent increases in tension development of isolated coronary artery rings (average EC50 of 42 ± 19 nM). Incubation of coronary arteries with S18886 (1 nM) significantly attenuated coronary vasoconstriction to U46619 resulting in a rightward shift of the EC50 to 187 ± 38 nM (P &lt; 0.02). Vehicle had no effect on U46619-induced contractions. Higher concentrations of S18886 (10nM and 100nM) dose-dependently reduced U46619-induced contractions by 77% ± 3 and 93% ± 6 respectively. S18886 (1 nM) antagonized coronary vasoconstriction of prostaglandin F2α (10 μM) by 68% ± 5 (P &lt; 0.0001) but had no effect on either acetylcholine or KCl-induced contraction. Data from this investigation indicate that S18886 is an effective antagonist of U46619-induced vasoconstriction in the porcine coronary circulation. While S18886 does not influence coronary smooth muscle response to either acetylcholine or activation of L-type Ca 2+ channels, attenuation of prostaglandin F 2α suggests the antagonists specificity may extend beyond TxA 2 receptor signaling. NIH R01HL158723 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

An In Vitro and In Silico Characterization of Salvia sclarea L. Methanolic Extracts as Spasmolytic Agents.

The use of medicinal plant species and their products is widespread in the field of gastrointestinal and respiratory diseases. This study aimed to evaluate the traditional use of Salvia sclarea L., clary sage, finding the possible mechanisms of its spasmolytic and bronchodilator actions in in vitro conditions supported by molecular docking analysis, along with the antimicrobial effects. Four dry extracts were prepared from the aerial parts of S. sclarea, using absolute or 80% (v/v) methanol by the method of a single-stage maceration or an ultrasound-assisted extraction. Characterization of the bioactive compounds by high-performance liquid chromatography indicated the presence of significant amounts of polyphenolics, with rosmarinic acid as the prevalent one. The spontaneous ileal contractions were best inhibited by the extract prepared with 80% methanol and maceration. The same extract was superior in the carbachol- and KCl-induced tracheal smooth muscle contractions, being the strongest bronchodilator agent. The most powerful relaxation of KCl-induced ileal contractions was achieved with the extract made of absolute methanol by maceration, while the 80% methanolic extract made with the ultrasound method generated the best spasmolytic effects in the acetylcholine-induced ileal contractions. Docking analysis suggested that apigenin-7-O-glucoside and luteolin-7-O-glucoside exhibited the highest binding affinity to voltage-gated calcium channels. Gram (+) bacteria were more susceptible to the effects of the extracts, particularly Staphylococcus aureus, in contrast to Gram (-) bacteria and Candida albicans. This is the first study to point out the influence of S. sclarea methanolic extracts on the gastrointestinal and respiratory spasm reduction, paving the way for their potential place in complementary medicine.

Dimethyl Sulfoxide Enhances Acetylcholine-Induced Contractions in Rat Urinary Bladder Smooth Muscle by Inhibiting Acetylcholinesterase Activities.

Dimethyl sulfoxide (DMSO) has been used not only as an experimental solvent, but also as a therapeutic agent for interstitial cystitis. The therapeutic effects of DMSO on interstitial cystitis are presumed to involve anti-inflammatory and analgesic effects. However, the effects of DMSO on urinary bladder smooth muscle (UBSM) have not been fully investigated. Thus, in this study, we investigated the effects of DMSO on rat UBSM contractions, and these effects were compared with those of acetone, which has a structure in which the sulfur of DMSO is replaced with carbon. DMSO (0.5-5%) enhanced acetylcholine (ACh)-induced contractions, whereas acetone (3 and 5%) suppressed them. Additionally, DMSO (5%) suppressed carbachol-induced contractions. DMSO/acetone (0.5-5%) inhibited 80 mM KCl-induced contractions in a concentration-dependent manner; however, the inhibitory effects of DMSO were weaker than those of acetone. The enhancing/suppressing effects of DMSO and acetone were almost completely abolished by wash out. DMSO and acetone (0.5-5%) inhibited recombinant human acetylcholinesterase (rhAChE) activity in a concentration-dependent manner. At 0.5 and 1%, the inhibitory effects of DMSO on rhAChE activity were more potent than those of acetone. These findings suggest that DMSO can enhance ACh-induced UBSM contractions and promote urinary bladder motility by inhibiting acetylcholinesterase (AChE), although DMSO also inhibits Ca2+ influx-mediated UBSM contractions. In addition, the sulfur atom in DMSO might play an important role in its enhancing effect on ACh-induced contractions by inhibiting AChE, as acetone did not enhance these contractions.

Sulodexide Develops Contraction in Human Saphenous Vein via Endothelium-Dependent Nitric Oxide Pathway.

Chronic venous disease (CVD) is a proqgressive and underestimated condition related to a vicious circle established by venous reflux and endothelial inflammation, leading to vein dilation and histology distortion, including loss of media tone. Sulodexide (SDX) is a drug restoring the glycocalyx that demonstrated endothelial protection and permeability regulation, together with anti-thrombotic and anti-inflammatory roles. In the lab it also exhibited vein contractility function. The aim of the present study was to show the possible role of endothelium and nitric oxide pathway on SDX's veno-contractile effect on human saphenous veins. The remnants of great saphenous vein (GSV) segments (n = 14) were harvested during coronary artery bypass graft surgery. They were dissected as endothelium-intact (n = 8) and denuded rings (n = 6). First, a viability test was carried out in bath with Krebs-Henseleit solution to investigate a control and basal tension value. After this, cumulative doses of SDX were applied to rings and contraction values were studied in endothelium-intact phenylephrine (PheE, 6 × 10-7 M) pre-contracted vein rings. Finally, endothelium-intact PheE pre-contacted vein rings were treated by nitric oxide synthase inhibitor Nω-nitro-L-arginine methyl ester (L-NAME, 10-4 M) for 10 min. Contraction protocol was applied, and contraction values were measured in cumulative doses of SDX. The same protocol was applied to endothelium-denuded vein rings to investigate the effect of SDX. Saphenous vein rings showed an increase in contraction to cumulative doses of SDX. In endothel-intact rings, KCL-induced contraction from 92.6% ± 0.3 to 112.9% ± 0.4 with cumulative SDX doses. However, SDX did not show any veno-contractile effect on endothel-denuded rings. In denuded rings contraction responses measured from 94.9% ± 0.3 to 85.2% ± 0.3 with increasing doses of SDX, indicating no significant change. Nitric oxide synthase inhibitor (L-NAME) prohibited the contraction response of the sulodexide in all dosages, indicating that the contractile function of SDX was mediated by endothelial derived nitric oxide. Results of endothel-intact and denuded rings with L-NAME showed a similar incline with denuded rings with SDX only. The results confirmed SDX's veno-contractile effect in human samples, by means of nitric oxide synthase pathways involvement.

Influence of lauric acid on the relaxation of corpus cavernosum in streptozotocin-induced diabetic male Wistar rats

BackgroundDiabetes mellitus is a global health challenge and has been recognised as a risk factor for erectile dysfunction. Dissatisfaction with standard medications has been reported by some patients, hence therapeutic plants are being considered as a viable alternative therapy, with their active components being investigated to create a standard regimen. Lauric acid is the most abundant constituent of coconut oil and is proposed to be responsible for its therapeutic properties. The corpus cavernosum plays an important role in erectile function with its relaxation favouring erection. This study thus sought to investigate the possible relaxant action and mechanism of lauric acid on the corpus cavernosum of diabetic male Wistar rats. Diabetes was induced by intraperitoneal injection of streptozotocin after which graded doses of lauric acid were administered orally to three groups of diabetic rats, once daily for 4 weeks. At the end of the experiment, the corpus cavernosal tissues of the rat penis were extracted. Following phenylephrine or potassium chloride (KCl)—induced contraction, relaxation response to acetylcholine and sodium nitroprusside was used to evaluate endothelium-dependent and nitric oxide-mediated relaxation, respectively.ResultsRelaxation response to acetylcholine, following pre-contraction with phenylephrine, was significantly decreased in the cavernosal tissues of diabetic untreated rats and was not significantly improved in lauric acid treated diabetic groups. Relaxation response to acetylcholine, following pre-contraction with KCl, was significantly decreased in the diabetic untreated group but was significantly improved in lauric acid treated diabetic groups at the lowest dose. Decreased relaxation response to sodium nitroprusside, following pre-contraction with phenylephrine in tissues of diabetic untreated rats, was significantly improved in lauric acid-treated diabetic groups at lower doses. Decreased relaxation response to sodium nitroprusside, following pre-contraction with KCl, was significantly improved in lauric acid-treated diabetic groups at all doses.ConclusionLauric acid improved relaxation of corpus cavernosum muscle in diabetic male rats by enhancing nitric oxide-mediated relaxing action of sodium nitroprusside and possibly inhibiting KCl-induced contraction.

Curcumanes E and F, two rare sesquiterpenoids with a dicyclo[3.3.1]nonane moiety, from Curcuma longa and their vasorelaxant activities.

Two new sesquiterpenoids, curcumanes E (1) and F (2), were isolated from the rhizome of Curcuma longa, and their structures and absolute configurations were examined using extensive spectroscopic analyses and ECD calculations. Interestingly, compounds 1 and 2 are diastereoisomers possessing a rare sesquiterpenoid skeleton that has been reported only once before. Both curcumanes E and F exhibit significant vasorelaxant effects against KCl-induced contraction of rat aortic rings, with EC50 values of 5.10 ± 0.79 and 5.58 ± 1.77 μM, respectively. These findings enrich the data concerning this rare type of sesquiterpenoids and further indicate that these rare sesquiterpenoids can effectively reduce blood pressure.

Abstract P140: Indanyloxyacetic Acid-94 Decreases Contraction In Uterine Arteries In Response To Phenylephrine And Decreases Response To Phenylephrine After Ca 2+ Replacement

Background: Chloride Intracellular Channels (CLICs) are a family of transmembrane proteins that can be present on the plasma membrane or the membranes of a number of organelles. These channels are redox and pH sensitive and present a unique target to understanding the vascular response to reactive oxygen species (ROS). By regulating oxidative stress, these channels may play a role in the pathology of vascular dysfunction. Uterine arteries were chosen as the focus of this project because of the lack of research involving its vascular function and role in disease. Hypothesis: This project hypothesizes that IAA94 will decrease vasoconstriction in response phenylephrine and enhance the relaxation response to acetylcholine in an endothelial-dependent manner. Methods: Vascular reactivity tests on wire myographs were performed in endothelium intact (E+) and denuded (E-) uterine arteries from Wistar rats. Rings were kept in Krebs solution at 37°C and constantly aerated with 95%O 2 /5%CO 2 . Concentration-response curves to phenylephrine (PE; 10 -9 -3x10 -5 M), and acetylcholine (ACH; 10 -9 - 3x10 -5 M) were performed in the absence or in the presence of IAA94 (50 uM). Vascular reactivity to 3*10 -6 M PE was also performed in Ca 2+ free Krebs solution with washout of intracellular Ca 2+ and replenishing of external Ca 2+ . A concentration response curve was completed to potassium chloride (KCL; 1mM - 100mM). Concentration-response curves were analyzed using non-linear regression analysis. Data are presented as mean ± S.E.M. Statistical significance set at p&lt;0.05. Data analyzed with GraphPad Prism 9.2.0. Results: In the E+ rings, IAA -94 inhibited contractile response to PE (pEC 50 : control 6.684 ± 0.1433 vs. IAA94 treated 5.616 ± 0.89, p&lt;0.0001). The E- had decreased inhibitory effects of IAA-94 on contractile response to PE (pEC 50 : control 5.832 ± 0.19 vs. IAA94 treated 5.32 ± 0.21, p= 0.2034). IAA94 treatment did not significantly change the contraction to KCL, while the IAA94 treatment did significantly decrease the rings response to PE after Ca 2+ washout and replenishment. Conclusion: The data show that IAA94 decreases the contractile response to PE in an endothelial dependent manner that is separate from the K + flux from KCL-induced contraction.