Contraction Of Aorta Research Articles

Leonuketal, a Spiroketal Diterpenoid from Leonurus japonicus.

An architecturally complex spiroketal diterpenoid, leonuketal (1), was isolated from the aerial parts of the plant Leonurus japonicus. This compound possessed an unprecedented tetracyclic skeleton that comprised a bridged spiroketal moiety fused with a ketal-γ-lactone unit. The structure and absolute configuration were determined by spectroscopic analyses, a modified Mosher's method, and ECD (electronic circular dichroism) calculations. Leonuketal (1) showed significant vasorelaxant activity against KCl-induced contraction of rat aorta, with the EC50 value of 2.32 μM.

6-Gingerol alleviates exaggerated vasoconstriction in diabetic rat aorta through direct vasodilation and nitric oxide generation.

The aim of the present study is to investigate the effect and potential mechanism of action of 6-gingerol on alterations of vascular reactivity in the isolated aorta from diabetic rats. Male Wistar rats were divided into two experimental groups, control and diabetics. Diabetes was induced by a single intraperitoneal injection of streptozotocin (50 mg kg−1), and the rats were left for 10 weeks to develop vascular complications. The effect of in vitro incubation with 6-gingerol (0.3–3 μM) on the vasoconstrictor response of the isolated diabetic aortae to phenylephrine and the vasodilator response to acetylcholine was examined. Effect of 6-gingerol was also examined on aortae incubated with methylglyoxal as an advanced glycation end product (AGE). To investigate the mechanism of action of 6-gingerol, the nitric oxide synthase inhibitor Nω-nitro-l-arginine methyl ester hydrochloride (100 μM), guanylate cyclase inhibitor methylene blue (5 μM), calcium-activated potassium channel blocker tetraethylammonium chloride (10 mM), and cyclooxygenase inhibitor indomethacin (5 μM) were added 30 minutes before assessing the direct vasorelaxant effect of 6-gingerol. Moreover, in vitro effects of 6-gingerol on NO release and the effect of 6-gingerol on AGE production were examined. Results showed that incubation of aortae with 6-gingerol (0.3–10 μM) alleviated the exaggerated vasoconstriction of diabetic aortae to phenylephrine in a concentration-dependent manner with no significant effect on the impaired relaxatory response to acetylcholine. Similar results were seen in the aortae exposed to methylglyoxal. In addition, 6-gingerol induced a direct vasodilation effect that was significantly inhibited by Nω-nitro-l-arginine methyl ester hydrochloride and methylene blue. Furthermore, 6-gingerol stimulated aortic NO generation but had no effect on AGE formation. In conclusion, 6-gingerol ameliorates enhanced vascular contraction in diabetic aortae, which may be partially attributed to its ability to increase the production of NO and stimulation of cyclic guanosine monophosphate.

Cecal inoculum peritonitis: An alternative model for sepsis vascular dysfunction study.

Sepsis is a life threatening condition that is characterized by the loss of vascular reactivity. The factor(s) responsible for the diminished vascular function seen in sepsis are not well understood. The purpose of this study was to characterize the vascular dysfunction from the rat cecal inoculum (CI) sepsis model using cecal ligation and puncture (CLP), and lipopolysaccharide (LPS) sepsis as reference models. Experiments were performed on isolated aorta from CI, CLP and LPS treated rats using a combination of pharmacological approaches. Phenylephrine (PE)-induced aortic contraction was significantly decreased in each model (p<0.05) and not normalized by L-NAME or indomethacin. The vascular response elicited in the CI model for acetylcholine (Ach) was more similar to that seen in the CLP than the LPS model. The removal of the endothelial layer increased sensitivity to L-NAME (p<0.05) in aortae from CI group. Inhibition of the large conductance Ca(2+)/voltage sensitive K(+) (BKCa) channel did not normalize PE hyporesponsiveness but did abolish sepsis-induced contractile oscillation. Inhibition of the voltage dependent Kv1.5 channel was not able to reverse the vascular hyporesponsiveness, however, inhibition of the ATP dependent (KATP) channel inhibition partially restored the contractile response (p<0.05). Elevation of VCAM expression and aortic structural alternation were observed in each model. These results suggest that the CI model may be an additional tool that could be used to investigate the mechanisms of vascular hyporesponsiveness in sepsis.

Role of α1D -adrenoceptors in vascular wall hypertrophy during angiotensin II-induced hypertension.

The invivo effect of continuous angiotensin II (Ang II) infusion on arterial blood pressure, vascular hypertrophy and α1 -adrenoceptors (α1 -ARs) expression was explored. Alzet(®) minipumps filled with Ang II (200ngkg(-1) min(-1) ) were subcutaneously implanted in male Wistar rats (3months-old). Groups of rats were also treated with losartan, an AT1 R antagonist, or with BMY 7378, a selective α1D -AR antagonist. Blood pressure was measured by tail-cuff; after 2 or 4weeks of treatment, vessels were isolated for functional and structural analyses. Angiotensin II increased systolic blood pressure. Phenylephrine-induced contraction in aorta was greater (40% higher) in Ang II-treated rats than in the controls, and similar effect occurred with KCl 80mm. Responses in tail arteries were not significantly different among the different groups. Angiotensin II decreased α1D -ARs without modifying the other α1 -ARs and induced an increase in media thickness (hypertrophy) in aorta, while no structural change occurred in tail artery. Losartan prevented and reversed hypertension and hypertrophy, while BMY 7378 prevented and reversed the aorta's hypertrophic response, without preventing or reversing hypertension. Findings indicate that Ang II-induced aortic hypertrophic response involves Ang II-AT1 Rs and α1D -ARs. Angiotensin II-induced α1D -AR-mediated vascular remodeling occurs independently of hypertension. Findings identify a α1D -AR-mediated process whereby Ang II influences aortic hypertrophy independently of blood pressure elevation.

Para-cresyl sulfate acutely impairs vascular reactivity and induces vascular remodeling.

Chronic kidney disease (CKD) is characterized by vascular remodeling and the retention of uremic toxins, several of which are independently associated with the high cardiovascular mortality rate in CKD patients. Whether the association between these uremic toxins and cardiovascular mortality is due to induction of vascular dysfunction and resulting vascular remodeling remains to be determined. This study evaluates the effects of para-cresyl sulfate (PCS), a newly identified uremic toxin, on vascular function and remodeling. PCS acutely induced oxidative stress in both endothelial and vascular smooth muscle cells, with a maximal effect at 0.15 mM, corresponding to the mean "uremic" concentration found in dialysis patients. PCS significantly increased within 30 min phenylephrine-induced contraction of mouse thoracic aorta, through direct activation of rho-kinase, independently of oxidative stress induction, as demonstrated by the capacity of rho-kinase inhibitor Y-27632 to abolish this effect. After exposure of the aorta to PCS for 48 h, we observed inward eutrophic remodeling, a hallmark of uremic vasculopathy characterized by a reduction of the area of both lumen and media, with unchanged media/lumen ratio. In conclusion, elevated PCS concentrations such as those observed in CKD patients, by promoting both vascular dysfunction and vascular remodeling, may contribute to the development of hypertension and to cardiovascular mortality in CKD.

Diverse effects of a 445 nm diode laser on isometric contraction of the rat aorta.

The usefulness of visible lasers in treating vascular diseases is controversial. It is probable that multiple effects of visible lasers on blood vessels and their unclear mechanisms have hampered the usefulness of this therapy. Therefore, elucidating the precise actions and mechanisms of the effects of lasers on blood vessels would provide insight into potential biomedical applications. Here, using organ chamber isometric contraction measurements, western blotting, patch-clamp, and en face immunohistochemistry, we showed that a 445 nm diode laser contracted rat aortic rings, both by activating endothelial nitric oxide synthase and by increasing oxidative stress. In addition to the effects on the endothelium, the laser also directly relaxed and contracted vascular smooth muscle by inhibiting L-type Ca(2+) channels and by activating protein tyrosine kinases, respectively. Thus, we conclude that exposure to 445 nm laser might contract and dilate blood vessels in the endothelium and smooth muscle via distinct mechanisms.

Rhythmic Aortic Contractions Induced by Electrical Stimulation In Vivo in the Rat.

For over a century, the behavior of the aorta and other large arteries has been described as passive elastic tubes in which no active contraction occurs in the smooth muscle wall. In response to pulsatile pressure changes, the vessels undergo a 'passive' elastic dilatation–contraction cycle, described as a “Windkessel” effect. However, Mangel and colleagues have presented evidence that is contrary to this view. They reported that in the rabbit, the aorta undergoes rhythmic 'active' (contraction) during the cardiac cycle; but these findings have been largely ignored. In the present study, we observed spontaneous contractions in synchrony with the heartbeat in another species (rat). In addition we demonstrate that aorta contractions are of neurogenic origin. Electrical stimulation of the aorta evoked contractions that occur at a rate that is in the range of the animal's heartbeat and are suppressed by tetrodotoxin and the alpha-adrenergic receptor blocker, phentolamine. Altogether, these findings indicate that aortic contractions are under neural control from the heart.

Abstract 624: Resolvin E1 Inhibits Thromboxane-Induced Contraction of Rat Aorta and Human Pulmonary Artery

Thromboxane is a vasoactive omega-6-derived lipid implicated in hypertension. Omega-3 fatty acid derivatives including resolvin (Rv) E1 have important roles in the resolution of inflammation, but their ability to mediate vasomotor activity is unknown. We assessed whether RvE1 modulates contraction of rat thoracic aorta and human pulmonary artery (HPA) in vitro. Rats were culled by CO2 inhalation and cervical dislocation, and the thoracic aorta was removed. HPA were obtained with informed consent from lung tissue of surgical patients at Southampton General Hospital. Segments of aorta or HPA were incubated in DMEM-F12 with or without RvE1 (10 nM, 100 nM or 300 nM) for 1 or 24 hours, and then mounted on a wire myograph. Mounted segments were bathed at 37[[Unable to Display Character: &amp;#61616;]]C in Kreb’s buffer, gassed (95%/5% O2/CO2) and set to 1.5 g of baseline tension. Functional integrity was confirmed by a contractile response to 125 mM KPSS. After washing to restore baseline tension, a cumulative concentration-response curve was defined to the stable thromboxane A2 mimetic U46619 (1 nM - 1 μM). Contractions are expressed as percent of KPSS response and differences determined by two-way ANOVA and by pairwise comparisons. In rat aorta, treatment with RvE1 (10 nM) significantly shifted the U46619 curve rightwards, increasing the EC50 value 13-fold from 0.13 μM to 1.75 μM after 1 hour (n=5), and 4-fold from 0.093 μM to 0.41 μM after 24 hours (n=5). In contrast, 300 nM RvE1 caused no significant change in EC50 (1 hour 0.11 μM; 24 hours 0.097 μM, n=5). In HPA segments, RvE1 (10 nM, 1 hour) increased the U46619 EC50 value 7-fold from 0.0079 μM to 0.054 μM (n=3), with a preliminary experiment suggesting a similar outcome after 24 hours. Higher concentrations of RvE1 had no significant effect, suggesting the relaxant action of RVE1 has a bell-shaped response curve. In preliminary experiments, RvE1 inhibited U-46619 contractions of bronchiolar airways from the same human donors. Resolvin E1 is known for its immunomodulatory actions on leukocytes and also inhibits U46619-induced aggregation of platelets, but our results are the first evidence that this pro-resolution mediator can also inhibit contractions of intact vasculature from rat and human lung induced by a thromboxane mimetic.

Mechanisms underlying uridine adenosine tetraphosphate-induced vascular contraction in mouse aorta: Role of thromboxane and purinergic receptors

Uridine adenosine tetraphosphate (Up4A), a novel endothelium-derived vasoactive agent, is proposed to play a role in cardiovascular disorders and induces aortic contraction through activation of cyclooxygenases (COXs). We and others demonstrated that activation of A1 or A3 adenosine receptors (ARs) results in vascular contraction via thromboxane (TX) A2 production. However, the mechanisms of Up4A-induced vascular contraction in mouse aorta are not understood. We hypothesize that Up4A-induced aortic contraction is through COX-derived TXA2 production, which requires activation of A1 and/or A3AR. Concentration responses to Up4A were conducted in isolated aorta. The TXB2 production, a metabolite of TXA2, was also measured. Up4A (10−9-10−5M) produced a concentration-dependent contraction >70%, which was markedly attenuated by COX and COX1 but not by COX2 inhibition. Notably, Up4A-induced aortic contraction was blunted by both TX synthase inhibitor ozagrel and TXA2 receptor (TP) antagonist SQ29548. Surprisingly, A3AR deletion had no effect on Up4A-induced contraction. Moreover, A1AR deletion or antagonism as well as A1/A3AR deletion potentiated Up4A-induced aortic contraction, suggesting a vasodilator influence of A1AR. In contrast, non-selective purinergic P2 receptor antagonist PPADS significantly blunted Up4A-induced aortic contraction to a similar extent as selective P2X1R antagonist MRS2159, the latter of which was further reduced by addition of ozagrel. Endothelial denudation almost fully attenuated Up4A-induced contraction. Furthermore, Up4A (3μM) increased TXB2 formation, which was inhibited by either MRS2159 or ozagrel. In conclusion, Up4A-induced aortic contraction depends on activation of TX synthase and TP, which partially requires the activation of P2X1R but not A1 or A3AR through an endothelium-dependent mechanism.

Allatotropin modulates myostimulatory and cardioacceleratory activities in Rhodnius prolixus (Stal).

Haematophagous insects can ingest large quantities of blood in a single meal and eliminate high volumes of urine in the next few hours. This rise in diuresis is possible because the excretory activity of the Malpighian tubules is facilitated by an increase in haemolymph circulation as a result of intensification of aorta contractions combined with an increase of the anterior midgut peristaltic waves. It has been previously described that haemolymph circulation during post-prandial diuresis is stimulated by the synergistic activity of allatotropin (AT) and serotonin in the kissing bug Triatoma infestans; resulting in an increase in aorta contractions. In the same species, AT stimulates anterior midgut and rectum muscle contractions to mix urine and feces and facilitate the voiding of the rectum. Furthermore, levels of AT in midgut and Malpighian tubules increased in the afternoon when insects are getting ready for nocturnal feeding. In the present study we describe the synergistic effect of AT and serotonin increasing the frequency of contractions of the aorta in Rhodnius prolixus. The basal frequency of contractions of the aorta in the afternoon is higher that the observed during the morning, suggesting the existence of a daily rhythmic activity. The AT receptor is expressed in the rectum, midgut and dorsal vessel, three critical organs involved in post-prandial diuresis. All together these findings provide evidence that AT plays a role as a myoregulatory and cardioacceleratory peptide in R. prolixus.

Des-aspartate angiotensin I (DAA-I) reduces endothelial dysfunction in the aorta of the spontaneously hypertensive rat through inhibition of angiotensin II-induced oxidative stress

Des-aspartate angiotensin I (DAA-I), an endogenous nonapeptide, counteracts several effects of angiotensin II on vascular tone. The aim of this study was to investigate the acute protective effect of DAA-I on endothelial function in the spontaneously hypertensive rat (SHR) as well as its effect on angiotensin II-induced contractions and oxidative stress. Aortic rings were incubated with DAA-I (0.1μM) for 30min prior to the assessment of angiotensin II-induced contractions (0.1nM–10μM) in WKY and SHR aortas. Total nitrate and nitrite levels were assessed using a colorimetric method and reactive oxygen species (ROS) were measured by dihydroethidium (DHE) fluorescence and lucigenin-enhanced chemiluminescence. The effect of DAA-I was also assessed against endothelium-dependent and -independent relaxations to acetylcholine and sodium nitroprusside, respectively. Angiotensin II-induced contractions were significantly reduced by DAA-I, losartan and tempol. Incubation with ODQ (soluble guanylyl cyclase inhibitor) and removal of the endothelium prevented the reduction of angiotensin II-induced contractions by DAA-I. Total nitrate and nitrite levels were increased in DAA-I, losartan and tempol treated-SHR tissues while ROS level was reduced by DAA-I and the latter inhibitors. In addition, DAA-I significantly improved the impaired acetylcholine-induced relaxation in SHR aortas whilst sodium nitroprusside-induced endothelium-independent relaxation remained unaffected. The present findings indicate that improvement of endothelial function by DAA-I in the SHR aorta is mediated through endothelium-dependent release of nitric oxide and inhibition of angiotensin II-induced oxidative stress.

Mechanisms of Uridine Adenosine Tetraphosphate (Up4A)‐induced Contraction in Mice Aorta: Role of Thromboxane (TXA2) and Purinergic Receptors (P2R)

Up4A, a novel endothelium‐derived vasoconstrictor, is proposed to play a role in cardiovascular disorders and induces aortic contraction through cyclooxygenases (COX). We demonstrated earlier that activation of A3 adenosine receptors (AR) results in aortic contraction via TXA2 production. However, the mechanisms of Up4A‐induced contraction are not understood. We hypothesize that Up4A‐induced contraction is via A3AR‐mediated TXA2 production. Concentration responses to Up4A were conducted in aorta from WT and A3AR KO. Up4A (10‐9‐10‐5 M) produced a dose‐dependent contraction (~80%), which was attenuated by non‐selective COX (indomethacin, 10 μM) and selective COX1 (SC560, 10 nM) but not by COX2 inhibition (NS398, 1 μM). Notably, Up4A‐induced contraction was blunted by TXA2 synthase inhibitor ozagrel (10 μM) and TXA2 receptor antagonist SQ29548 (1 μM). Non‐selective AR antagonist 8PST (100 μM) nor A3AR deletion affected Up4A‐induced contraction. However, both non‐selective P2R antagonist PPADS (10 μM) and P2X1R antagonist MRS2159 (30 μM) significantly attenuated Up4A‐induced contraction (~46% and 40%), respectively. Combination of ozagrel with MRS2159 further decreased this effect (~20%). Endothelial denudation almost fully reduced Up4A‐induced contraction. Furthermore, TXA2 production increased in vessels treated with Up4A (3 μM) (26.6±0.5 vs. 83.4±0.8 pg/mg), which was inhibited by either MRS2159 (49.0±0.7 pg/mg) or Ozagrel (42.4±0.5 pg/mg). In conclusion, Up4A‐induced contraction is via TXA2 production, which partially requires the activation of P2X1R but not A3AR through an endothelium‐dependent mechanism (Supported by HL 027339, HL 094447 and MEPSCKL201301).

Vascular Reactivity of Rat, Guinea‐pig, Rabbit and Human Vessels to Bufadienolides and Cardenolides

Cardenolides and bufodienolides are Na+-K+-ATPase (NKA) inhibitors. The aim of the present study was to evaluate the response to such compounds of vessels from different species in order to compare potency and efficacy. The experimental protocols were approved by the Animal Care and Ethics Committee of the Ceara State University. The aortic rings and mesenteric artery for isometric recordings of contractions in response to cumulative addition of OUA, BUF, DIG (0.1-100 µM). The contractions were expressed as percentage of the maximal contraction elicited by phenylephrine. Ouabain, up to 100 µM, promoted no contraction in rat aorta but promoted a slow onset contraction that attained a maximum of 71.5±14.8% and 101.2±8.5% in guinea-pig and rabbit tissue, respectively. Bufalin promoted slow onset contractions after 30 and 100 µM that reached a maximum of 20.6 ± 5.2%,55.0±10.5% and 94±19.8% in tissues gathered from rats, guinea-pigs and rabbits, respectively. On the other hand, digoxin did not elicit contraction in rabbit or rat aortic rings but elicited a similar slow onset that attained its maximum after more than 50 minutes and reached 79.7±15.6% in guinea-pig tissues. In human aortic rings in response to 100 µM bufalin or ouabain reached a maximum of 96.7±24.4% or 140±26.7%, respectively. In the 2nd branch of the mesenteric artery, BUF promoted a slow contractile response (46 % ± 9.6 %) only at a dose of 100 µM.Pretreatment with guanethidine (GUA + BUF) significantly attenuated BUF vasoconstriction in aortic rings (39.7% ± 8.4) and prazosin (1µM) completely blocked the contraction, suggesting and indirect noradrenergic activation.

Acute Ozone (O 3 ) Exposure Enhances Aortic Contraction in Healthy Rats while Exacerbating Pulmonary Injury in Diabetics

Air pollution exposure affects health adversely in individuals with type 2 diabetes (T2D) and diet induced obesity (DIO). We hypothesized that T2D and DIO would exacerbate O3 induced pulmonary responses and alter arterial reactivity. Male Wistar and Goto Kakizaki (GK) rats, a lean T2D Wistar derived model, were fed a normal or high cholesterol diet (HCD) for 12 wks starting at 4 wks of age. After the 12 wk diet, rats were exposed to filtered air or 1 ppm O3, 6h/d for 1 or 2 days. Wistars had greater body weights with lower body fat percentages than GKs. HCD induced DIO in both strains as evidenced by increased body weight and body fat percentages. Biomarkers of lung injury including protein, albumin, lactate dehydrogenase and N-acetyl glucosaminidase increased after O3 exposure in both strains. These levels were not altered by DIO but were exacerbated in GKs despite a smaller exposure due to a lower minute volume. Aortic segments were isolated for myographic assessment of vascular reactivity in response to pharmacological intervention after the 2 day O3 exposure. Phenylephrine and KCl increased aortic contractile force in the O3 exposed Wistars, but this response was not found in the T2D or DIO models. Aortas isolated from Wistars had decreased vasorelaxation in response to acetylcholine (ACh) regardless of diet or exposure. L-NAME did not fully block ACh induced vasorelaxation in the GKs, suggesting nitric oxide independent pathways may be involved in vasorelaxation responses. These data indicate that O3 exposure may induce arterial dysfunction in healthy individuals and augment lung injury in diabetics. (This abstract does not reflect US EPA Policy; Research supported by ORISE)

Pharmacological basis for the folkloric uses of &lt;i&gt;Buxus wallichiana&lt;/i&gt; in gastrointestinal, respiratory and vascular disorders

&lt;p&gt;&lt;em&gt;In vitro&lt;/em&gt; study was carried out to explore the pharmacological basis of crude extract of &lt;em&gt;Buxus wallichiana &lt;/em&gt;for its folkloric uses in gastrointestinal, respiratory and vascular disorders. In jejunum preparations, crude extract (0.03 ± 1.0 mg/mL) caused a transient spasmogenic effect followed by the spasmolytic effect at higher doses (3.0–10 mg/mL). In atropinized jejunum preparation, crude extract inhibited the spontaneous and K&lt;sup&gt;+ &lt;/sup&gt;(80 mM)-induced contraction, suggesting that spasmolytic effect is mediated through the Ca&lt;sup&gt;+2&lt;/sup&gt;-channel blockade. The Ca&lt;sup&gt;+2&lt;/sup&gt;-channel blockade effect was confirmed when pretreatment of tissue with extract produced a dose-dependent shift in Ca&lt;sup&gt;+2 &lt;/sup&gt;concentration-response curves to the right, similarly as verapamil. Furthermore, crude extract exhibited non-specific relaxant effect on carbachol- (1 µM) and K&lt;sup&gt;+ &lt;/sup&gt;(80 mM)-induced tracheal contractions, suggesting the coexistence of anticholi-nergic and Ca&lt;sup&gt;+2&lt;/sup&gt;-antagonistic properties. Moreover, it relaxed the K&lt;sup&gt;+ &lt;/sup&gt;(80 mM)- and phenylephrine (1 µM)-induced contraction in rabbit aorta, suggesting the Ca&lt;sup&gt;+2&lt;/sup&gt;-channel blockade. These findings may validate the folkloric uses of &lt;em&gt;B. wallichiana&lt;/em&gt; in constipation, bronchitis, asthma and hypertension.&lt;/p&gt;

Voluntary Exercise Decreases Atherosclerosis in Nephrectomised ApoE Knockout Mice

Cardiovascular disease is the main cause of morbidity and mortality in patients with kidney disease. The effectiveness of exercise for cardiovascular disease that is accelerated by the presence of chronic kidney disease remains unknown. The present study utilized apolipoprotein E knockout mice with 5/6 nephrectomy as a model of combined kidney disease and cardiovascular disease to investigate the effect of exercise on aortic plaque formation, vascular function and systemic inflammation. Animals were randomly assigned to nephrectomy or control and then to either voluntary wheel running exercise or sedentary. Following 12-weeks, aortic plaque area was significantly (p<0.05, d=1.2) lower in exercising nephrectomised mice compared to sedentary nephrectomised mice. There was a strong, negative correlation between average distance run each week and plaque area in nephrectomised and control mice (r=–0.76, p=0.048 and r=–0.73, p=0.062; respectively). In vitro aortic contraction and endothelial-independent and endothelial-dependent relaxation were not influenced by exercise (p>0.05). Nephrectomy increased IL-6 and TNF-α concentrations compared with control mice (p<0.001 and p<0.05, respectively), while levels of IL-10, MCP-1 and MIP-1α were not significantly influenced by nephrectomy or voluntary exercise (p>0.05). Exercise was an effective non-pharmacologic approach to slow cardiovascular disease in the presence of kidney disease in the apolipoprotein E knockout mouse.

Hydrogen sulfide ameliorates cardiovascular dysfunction induced by cecal ligation and puncture in rats

Hydrogen sulfide (H2S) is an endogenously produced gaseous messenger that participates in regulation of cardiovascular functions. This study evaluates the possible protective effect of H2S in cardiovascular dysfunction induced by cecal ligation and puncture (CLP) in rats. After 24 h of induction of CLP, heart rate (HR), mortality, cardiac and inflammation biomarkers (creatine kinase-MB (CK-MB) isozyme, cardiac troponin I (cTnI), C-reactive protein (CRP), and lactate dehydrogenase (LDH)), in vitro vascular reactivity, histopathological examination, and oxidative biomarkers (malondialdehyde (MDA), reduced glutathione (GSH), and superoxide dismutase (SOD)) were determined. CLP induced elevations in HR, mortality, serum CK-MB, cTnI, CRP, and LDH, in addition to impaired aortic contraction to potassium chloride and phenylephrine and relaxation to acetylcholine without affecting sodium nitroprusside responses. Moreover, CLP increased cardiac and aortic MDA and decreased SOD, without affecting GSH and caused a marked subserosal and interstitial inflammation in endocardium. Sodium hydrosulfide, but not the irreversible inhibitor of H2S synthesis dl-propargyl glycine, protected against CLP-induced changes in HR, mortality, cardiac and inflammatory biomarkers, oxidative stress, and myocardium histopathological changes without affecting vascular dysfunction. Our results confirm that H2S can attenuate CLP-induced cardiac, but not vascular, dysfunction possibly through its anti-inflammatory and antioxidant effects.

Endothelium and the effect of activated neutrophils on arterial smooth muscle.

The aim of the study was to analyze the involvement of the endothelium in the effects of neutrophils (PMNL) on phenylephrine-precontracted isolated rings of the rat thoracic aorta and to compare their effects with those of peroxynitrite (ONOO−) and hypochlorous acid (HOCl). Activated PMNL-induced contraction of the precontracted aorta was prevented by the blockade of NO-synthase and by endothelium removal. In the endothelium-free preparations, the effect of PMNL reappeared in the presence of sodium nitroprusside. The effect of ONOO– and HOCl significantly differed from that of activated PMNL both in the presence and absence of the endothelium. It is therefore likely that neither ONOO– nor HOCl generated by transformation of superoxide anion radical (O2•–) produced by PMNL is involved in their action. Reduction of the relaxant effect of nitric oxide derived from the endothelium by O2•– seems to be the keystone mechanism in generation of PMNL-induced contraction.

Presystolic flow in ascending aorta in a case of left ventricular diastolic dysfunction

A 65 years old hypertensive presented with effort breathlessness. Echocardiography revealed significant concentric remodeling of left ventricle. (relative wall thickness – 0.86) with significantly impaired relaxation (E/A – 0.54 and Ea/Aa – 0.52). Doppler evaluation of flow in ascending aorta revealed a presystolic flow which coincided with P wave of ECG and A wave of mitral flow. This finding suggests increased stiffness of left ventricle resulting in significant increase in left ventricular pressure during left atrial contraction and presystolic flow in aorta. Our case shows that all cases of grade 1 diastolic dysfunction are not alike. Presystolic flow in ascending aorta suggests greater degree of diastolic dysfunction than what is apparent from conventional criteria.

Activation of Toll-like receptor 3 increases mouse aortic vascular smooth muscle cell contractility through ERK1/2 pathway.

Activation of Toll-like receptor 3 (TLR3), a pattern recognition receptor of the innate immune system, is associated with vascular complications. However, whether activation of TLR3 alters vascular contractility is unknown. We, therefore, hypothesized that TLR3 activation augments vascular contractility and activates vascular smooth muscle cell (VSMC) contractile apparatus proteins. Male mice were treated with polyinosinic-polycytidylic acid (Poly I:C group, 14days), a TLR3 agonist; control mice received saline (vehicle, 14days). At the end of protocol, blood pressure was measured by tail cuff method. Aortas were isolated and assessed for contractility experiments using a wire myograph. Aortic protein content was used to determine phosphorylated/total interferon regulatory factor 3 (IRF3), a downstream target of TLR3 signaling, and ERK1/2 using Western blot. We investigated the TLR3/IRF3/ERK1/2 signaling pathway and contractile-related proteins such as phosphorylated/total myosin light chain (MLC) and caldesmon (CaD) in aortic VSMC primary cultures. Poly I:C-treated mice exhibited (vs. vehicle-treated mice) (1) elevated systolic blood pressure. Moreover, Poly I:C treatment (2) enhanced aortic phenylephrine-induced maximum contraction, which was suppressed by PD98059 (ERK1/2 inhibitor), and (3) increased aortic levels of phosphorylated IRF3 and ERK1/2. Stimulation of mouse aortic VSMCs with Poly I:C resulted in increased phosphorylation of IRF3, ERK1/2, MLC, and CaD. Inhibition of ERK1/2 abolished Poly I:C-mediated phosphorylation of MLC and CaD. Our data provide functional evidence for the role of TLR3 in vascular contractile events, suggesting TLR3 as a potential new therapeutic target in vascular dysfunction and regulation of blood pressure.