The basal endothelial inhibitory influence on vascular tone is not affected in nitroglycerin-tolerant rat aorta

1994 ◽  
Vol 72 (9) ◽  
pp. 1094-1097 ◽  
Author(s):  
J. Van de Voorde ◽  
S. Vyt ◽  
B. Vanheel
Keyword(s):  
Nitric Oxide ◽  
Methylene Blue ◽  
Smooth Muscle ◽  
Vascular Tone ◽  
Prolonged Exposure ◽  
Rat Aorta ◽  
Nitrate Tolerance ◽  
Inhibitory Influence ◽  
And Control

Prolonged exposure to nitrovasodilators produces tolerance and dependence. Nitrovasodilators exert their action on vascular smooth muscle cells by activation of guanylyl cyclase. Nitrates share this mechanism with endothelial NO, which exerts a continuous inhibitory influence on vascular tone. Whether the basal inhibitory endothelial influence might be affected in rat aorta exposed in vitro to a tolerance-inducing concentration of nitroglycerin was investigated in this study. It was found that the basal inhibitory influence, assessed as its inhibitory influence on norepinephrine-induced contraction, and as the contractile effect of N-nitro-L-arginine methyl ester or methylene blue, was the same in nitroglycerin-tolerant and control aortic rings. Our results give an indication that changes in basal inhibitory endothelial influence are not involved in the phenomena of nitrate tolerance and nitrate dependence.Key words: nitroglycerin, nitrates, tolerance, endothelium, nitric oxide.

Levobupivacaine-induced contraction of isolated rat aorta is calcium dependent

2011 ◽  
Vol 89 (7) ◽  
pp. 467-476 ◽  
Author(s):  
Ji Seok Baik ◽  
Ju-Tae Sohn ◽  
Seong-Ho Ok ◽  
Jae-Gak Kim ◽  
Hui-Jin Sung ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Smooth Muscle ◽  
Calcium Influx ◽  
Rat Aorta ◽  
Isometric Tension ◽  
Guanosine Monophosphate ◽  
Response Curves ◽  
Calcium Dependent ◽  
Isolated Rat

Levobupivacaine is a long-acting local anesthetic that intrinsically produces vasoconstriction in isolated vessels. The goals of this study were to investigate the calcium-dependent mechanism underlying levobupivacaine-induced contraction of isolated rat aorta in vitro and to elucidate the pathway responsible for the endothelium-dependent attenuation of levobupivacaine-induced contraction. Isolated rat aortic rings were suspended to record isometric tension. Cumulative levobupivacaine concentration–response curves were generated in either the presence or absence of the antagonists verapamil, nifedipine, SKF-96365, 2-aminoethoxydiphenylborate, Gd3+, NW-nitro-l-arginine methyl ester (L-NAME), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), and methylene blue, either alone or in combination. Verapamil, nifedipine, SKF-96365, 2-aminoethoxydiphenylborate, low calcium concentrations, and calcium-free Krebs solution attenuated levobupivacaine-induced contraction. Gd3+ had no effect on levobupivacaine-induced contraction. Levobupivacaine increased intracellular calcium levels in vascular smooth muscle cells. L-NAME, ODQ, and methylene blue increased levobupivacaine-induced contraction in endothelium-intact aorta. SKF-96365 attenuated calcium-induced contraction in a previously calcium-free isotonic depolarizing solution containing 100 mmol/L KCl. Levobupivacaine-induced contraction of rat aortic smooth muscle is mediated primarily by calcium influx from the extracellular space mainly via voltage-operated calcium channels and, in part, by inositol 1,4,5-trisphosphate receptor-mediated release of calcium from the sarcoplasmic reticulum. The nitric oxide – cyclic guanosine monophosphate pathway is involved in the endothelium-dependent attenuation of levobupivacaine-induced contraction.

Differential effects of nitrovasodilators and nitric oxide on porcine tracheal and bronchial muscle in vitro

1994 ◽  
Vol 77 (3) ◽  
pp. 1142-1147 ◽  
Author(s):  
K. Stuart-Smith ◽  
T. C. Bynoe ◽  
K. S. Lindeman ◽  
C. A. Hirshman
Keyword(s):  
Nitric Oxide ◽  
Methylene Blue ◽  
Smooth Muscle ◽  
Sodium Nitroprusside ◽  
Airway Smooth Muscle ◽  
Muscle Relaxation ◽  
Ringer Solution ◽  
Smooth Muscle Relaxation ◽  
Response Curves

Nitrovasodilators and nitric oxide relax airway smooth muscle. The mechanism by which nitrovasodilators are thought to act is by release of nitric oxide, but the importance of nitric oxide in nitrovasodilator-induced airway smooth muscle relaxation is unclear. The aim of this study was to compare the relaxing effects of nitric oxide itself with those of nitrovasodilators in porcine tracheal muscle and intrapulmonary airways and to investigate the mechanisms involved. Strips of porcine tracheal smooth muscle, rings of bronchi, and strips of bronchi from the same animal were suspended in organ chambers in modified Krebs Ringer solution (95% O2–5% CO2, 37 degrees C). Tissues were contracted with carbachol, and concentration-response curves to nitric oxide, sodium nitroprusside, and SIN-1 (an active metabolite of molsidomine) were obtained. All tissues relaxed to sodium nitroprusside, SIN-1, and nitric oxide. The relaxation to nitric oxide but not to SIN-1 or sodium nitroprusside was inhibited by methylene blue. Tissues pretreated with methylene blue that failed to relax to nitric oxide were, however, relaxed by sodium nitroprusside. These results demonstrate that nitrovasodilators relax airways by a mechanism other than by or in addition to the release of nitric oxide.

Vasorelaxant Effect of Novel Nitric Oxide-Hydrogen Sulfide Donor Chalcone in Isolated Rat Aorta: Involvement of cGMP Mediated sGC and Potassium Channel Activation

2020 ◽  
Vol 13 (2) ◽  
pp. 126-136
Author(s):  
Amol Sherikar ◽  
Rakesh Dhavale ◽  
Manish Bhatia
Keyword(s):  
Nitric Oxide ◽  
Methylene Blue ◽  
Hydrogen Sulfide ◽  
Potassium Channel ◽  
Rat Aorta ◽  
Tetraethylammonium Chloride ◽  
Vasorelaxant Effect ◽  
Activation Assay ◽  
Isolated Rat

Background and Objective: : Recently, nitric oxide (NO) and hydrogen sulfide (H2S) donating moieties were extensively studied for their role in the vasculature as they are responsible for many cellular and pathophysiological functioning. The objective of the present study is to evaluate novel NO and H2S donating chalcone moieties on isolated rat aorta for vasorelaxation, and to investigate the probable mechanism of action. Methods:: To extend our knowledge of vasorelaxation by NO and H2S donor drugs, here we investigated the vasorelaxing activity of novel NO and H2S donating chalcone moieties on isolated rat aorta. The mechanism of vasorelaxation by these molecules was investigated by performing in vitro cGMP mediated sGC activation assay and using Tetraethylammonium chloride (TEA) as a potassium channel blocker and Methylene blue as NO blocker. Results:: Both NO and H2S donating chalcone moieties were found to be potent vasorelaxant. The compound G4 and G5 produce the highest vasorelaxation with 3.716 and 3.789 M of pEC50, respectively. After the addition of TEA, G4 and G5 showed 2.772 and 2.796 M of pEC50, respectively. The compounds Ca1, Ca2, and D7 produced significant activation and release of cGMP mediated sGC which was 1.677, 1.769 and 1.768 M of pEC50, respectively. Conclusion: : The vasorelaxation by NO-donating chalcones was blocked by Methylene blue but it did not show any effect on H2S donating chalcones. The vasorelaxing potency of NO-donating molecules was observed to be less affected by the addition of TEA but H2S donors showed a decrease in both efficacy and potency. The cGMP release was more in the case of NO-donating molecules. The tested compounds were found potent for relaxing vasculature of rat aorta.

Regional differentiation in the rat aorta: effects of cyclooxygenase inhibitors

1997 ◽  
Vol 273 (3) ◽  
pp. H1478-H1483 ◽  
Author(s):  
D. Schachter ◽  
J. C. Sang
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Cyclic Nucleotide ◽  
Rat Aorta ◽  
Cyclic Nucleotide Phosphodiesterase ◽  
Cyclooxygenase Inhibitors ◽  
Regional Differentiation ◽  
Phosphodiesterase Activity ◽  
Dynamic Regulation

Rat aortic endothelium is differentiated regionally for signaling the underlying smooth muscle via nitric oxide to increase the level of guanosine 3',5'-cyclic monophosphate (cGMP) [R.E. Abbott and D. Schachter. Am. J. Physiol. 266 (Heart Circ. Physiol. 35): H2287-H2295, 1994]. Maximal activity is just distal to the aortic arch, i.e., in the "windkessel" region, and diminishes peripherally. This report describes the same pattern of endothelial differentiation for a second signal arising from the cyclooxygenase arm of the eicosanoid pathway. Treatment of sequential segments of rat aorta in vitro with indomethacin (50 microM) or acetylsalicylate (100 microM) increased the cGMP content selectively in aortic segments prepared from the windkessel region. The indomethacin effect was eliminated by denuding the endothelium or by inhibiting cyclic nucleotide phosphodiesterase activity. Prostaglandin H2 was identified as a cyclooxygenase product involved in this signal pathway because treatment with the compound decreased cGMP levels, and this effect was eliminated by inhibiting cyclic nucleotide phosphodiesterase activity. Endothelial regulation of smooth muscle cGMP via nitric oxide and cyclooxygenase pathways supports the concept of dynamic regulation of aortic wall properties in the windkessel region.

In vivo attenuation of endothelium-dependent pulmonary vasodilation by methylene blue

1991 ◽  
Vol 71 (2) ◽  
pp. 735-741 ◽  
Author(s):  
J. R. Fineman ◽  
M. R. Crowley ◽  
M. A. Heymann ◽  
S. J. Soifer
Keyword(s):  
Methylene Blue ◽  
Smooth Muscle ◽  
Arterial Pressure ◽  
Guanylate Cyclase ◽  
Vascular Tone ◽  
Pulmonary Arterial Pressure ◽  
Pulmonary Vasodilation ◽  
Pulmonary Arterial

In vitro evidence suggests that resting pulmonary vascular tone and endothelium-dependent pulmonary vasodilation are mediated by changes in vascular smooth muscle concentrations of guanosine 3′,5′-cyclic monophosphate (cGMP). We investigated this hypothesis in vivo in 19 mechanically ventilated intact lambs by determining the hemodynamic effects of methylene blue (a guanylate cyclase inhibitor) and then by comparing the hemodynamic response to five vasodilators during pulmonary hypertension induced by the infusion of U-46619 (a thromboxane A2 mimic) or methylene blue. Methylene blue caused a significant time-dependent increase in pulmonary arterial pressure. During U-46619 infusions, acetylcholine, ATP-MgCl2, sodium nitroprusside, isoproterenol, and 8-bromo-cGMP decreased pulmonary arterial pressure. During methylene blue infusions, the decreases in pulmonary arterial pressure caused by acetylcholine and ATP-MgCl2 (endothelium-dependent vasodilators) and sodium nitroprusside (an endothelium-independent guanylate cyclase-dependent vasodilator) were attenuated by greater than 50%. The decreases in pulmonary arterial pressure caused by isoproterenol and 8-bromo-cGMP (endothelium-independent vasodilators) were unchanged. This study in intact lambs supports the in vitro evidence that changes in vascular smooth muscle cell concentrations of cGMP in part mediate resting pulmonary vascular tone and endothelium-dependent pulmonary vasodilation.

scholarly journals Endothelium-Derived Hyperpolarizing Factor and Myoendothelial Coupling: The in vivo Perspective

2020 ◽  
Vol 11 ◽  
Author(s):  
Kjestine Schmidt ◽  
Cor de Wit
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Membrane Potential ◽  
Vascular Tone ◽  
Radial Spread ◽  
Distinct Features ◽  
Type Response ◽  
Chemical Mediators

The endothelium controls vascular tone adopting blood flow to tissue needs. It releases chemical mediators [e.g., nitric oxide (NO), prostaglandins (PG)] and exerts appreciable dilation through smooth muscle hyperpolarization, thus termed endothelium-dependent hyperpolarization (EDH). Initially, EDH was attributed to release of a factor, but later it was suggested that smooth muscle hyperpolarization might be derived from radial spread of an initial endothelial hyperpolarization through heterocellular channels coupling these vascular cells. The channels are indeed present and formed by connexins that enrich in gap junctions (GJ). In vitro data suggest that myoendothelial coupling underlies EDH-type dilations as evidenced by blocking experiments as well as simultaneous, merely identical membrane potential changes in endothelial and smooth muscle cells (SMCs), which is indicative of coupling through ohmic resistors. However, connexin-deficient animals do not display any attenuation of EDH-type dilations in vivo, and endothelial and SMCs exhibit distinct and barely superimposable membrane potential changes exerted by different means in vivo. Even if studied in the exact same artery EDH-type dilation exhibits distinct features in vitro and in vivo: in isometrically mounted vessels, it is rather weak and depends on myoendothelial coupling through connexin40 (Cx40), whereas in vivo as well as in vitro under isobaric conditions it is powerful and independent of myoendothelial coupling through Cx40. It is concluded that EDH-type dilations are distinct and a significant dependence on myoendothelial coupling in vitro does not reflect the situation under physiologic conditions in vivo. Myoendothelial coupling may act as a backup mechanism that is uncovered in the absence of the powerful EDH-type response and possibly reflects a situation in a pathophysiologic environment.

scholarly journals Effects of Hyperglycemia on Vascular Smooth Muscle Ca2+Signaling

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Nahed El-Najjar ◽  
Rashmi P. Kulkarni ◽  
Nancy Nader ◽  
Rawad Hodeify ◽  
Khaled Machaca
Keyword(s):  
Insulin Resistance ◽  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Vascular Smooth Muscle ◽  
Complex Disease ◽  
Prolonged Exposure ◽  
In Vitro System ◽  
A7r5 Cells

Diabetes is a complex disease that is characterized with hyperglycemia, dyslipidemia, and insulin resistance. These pathologies are associated with significant cardiovascular implications that affect both the macro- and microvasculature. It is therefore important to understand the effects of various pathologies associated with diabetes on the vasculature. Here we directly test the effects of hyperglycemia on vascular smooth muscle (VSM) Ca2+signaling in an isolated in vitro system using the A7r5 rat aortic cell line as a model. We find that prolonged exposure of A7r5 cells to hyperglycemia (weeks) is associated with changes to Ca2+signaling, including most prominently an inhibition of the passive ER Ca2+leak and the sarcoplasmic reticulum Ca2+-ATPase (SERCA). To translate these findings to the in vivo condition, we used primary VSM cells from normal and diabetic subjects and find that only the inhibition of the ER Ca2+leaks replicates in cells from diabetic donors. These results show that prolonged hyperglycemia in isolation alters the Ca2+signaling machinery in VSM cells. However, these alterations are not readily translatable to the whole organism situation where alterations to the Ca2+signaling machinery are different.

Nitric oxide synthase inhibitors 7- and 6-nitroindazole relax smooth muscle in vitro

1994 ◽  
Vol 256 (1) ◽  
pp. R5-R6 ◽  
Author(s):  
Andrew D. Medhurst ◽  
Carol Greenlees ◽  
Andrew A. Parsons ◽  
Susan J. Smith
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Nitric Oxide Synthase ◽  
Nitric Oxide Synthase Inhibitors ◽  
Oxide Synthase

Comparison of the hemodynamic effects of nitric oxide and endothelium-dependent vasodilators in intact lungs

1990 ◽  
Vol 68 (2) ◽  
pp. 735-747 ◽  
Author(s):  
S. L. Archer ◽  
K. Rist ◽  
D. P. Nelson ◽  
E. G. DeMaster ◽  
N. Cowan ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Methylene Blue ◽  
Pulmonary Hypertension ◽  
Feedback Inhibition ◽  
Pressor Response ◽  
Pulmonary Vasculature ◽  
Hemodynamic Effects ◽  
Isolated Lung

The effects of endothelium-dependent vasodilation on pulmonary vascular hemodynamics were evaluated in a variety of in vivo and in vitro models to determine 1) the comparability of the hemodynamic effects of acetylcholine (ACh), bradykinin (BK), nitric oxide (NO), and 8-bromo-guanosine 3′,5′-cyclic monophosphate (cGMP), 2) whether methylene blue is a useful inhibitor of endothelium-dependent relaxing factor (EDRF) activity in vivo, and 3) the effect of monocrotaline-induced pulmonary hypertension on the responsiveness of the pulmonary vasculature to ACh. In isolated rat lungs, which were preconstricted with hypoxia, ACh, BK, NO, and 8-bromo-cGMP caused pulmonary vasodilation, which was not inhibited by maximum tolerable doses of methylene blue. Methylene blue did not inhibit EDRF activity in any model, despite causing increased pulmonary vascular tone and responsiveness to various constrictor agents. There were significant differences in the hemodynamic characteristics of ACh, BK, and NO. In the isolated lung, BK and NO caused transient decreases of hypoxic vasoconstriction, whereas ACh caused more prolonged vasodilation. Pretreatment of these lungs with NO did not significantly inhibit ACh-induced vasodilation but caused BK to produce vasoconstriction. Tachyphylaxis, which was agonist specific, developed with repeated administration of ACh or BK but not NO. Tachyphylaxis probably resulted from inhibition of the endothelium-dependent vasodilation pathway proximal to NO synthesis, because it could be overcome by exogenous NO. Pretreatment with 8-bromo-cGMP decreased hypoxic pulmonary vasoconstriction and, even when the hypoxic pressor response had largely recovered, subsequent doses of ACh and NO failed to cause vasodilation, although BK produced vasoconstriction. These findings are compatible with the existence of feedback inhibition of the endothelium-dependent relaxation by elevation of cGMP levels. Responsiveness to ACh was retained in lungs with severe monocrotaline-induced pulmonary hypertension. Many of these findings would not have been predicted based on in vitro studies and illustrate the importance for expanding studies of EDRF to in vivo and ex vivo models.

Melatonin potentiates contractile responses to serotonin in isolated porcine coronary arteries

2001 ◽  
Vol 280 (1) ◽  
pp. H76-H82 ◽  
Author(s):  
Qiong Yang ◽  
Elizabeth Scalbert ◽  
Philippe Delagrange ◽  
Paul M. Vanhoutte ◽  
Stephen T. O'Rourke
Keyword(s):  
Nitric Oxide ◽  
Methylene Blue ◽  
Smooth Muscle ◽  
Coronary Arteries ◽  
Isometric Tension ◽  
Maximal Response ◽  
Melatonin Receptor ◽  
Vasomotor Tone ◽  
Vasoconstrictor Response ◽  
Coronary Vasomotor Tone

The present study was designed to determine the effects of melatonin on coronary vasomotor tone. Porcine coronary arteries were suspended in organ chambers for isometric tension recording. Melatonin (10−10-10−5 M) itself caused neither contraction nor relaxation of the tissues. Serotonin (10−9-10−5 M) caused concentration-dependent contractions of coronary arteries, and in the presence of melatonin (10−7 M) the maximal response to serotonin was increased in rings with but not without endothelium. In contrast, melatonin had no effect on contractions produced by the thromboxane A2 analog U-46619 (10−10-10−7 M). The melatonin-receptor antagonist S-20928 (10−6 M) abolished the potentiating effect of melatonin on serotonin-induced contractions in endothelium-intact coronary arteries, as did treatment with 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (10−5 M), methylene blue (10−5 M), or NG -nitro-l-arginine (3 × 10−5 M). In tissues contracted with U-46619, serotonin caused endothelium-dependent relaxations that were inhibited by melatonin (10−7 M). Melatonin also inhibited coronary artery relaxation induced by sodium nitroprusside (10−9-10−5 M) but not by isoproterenol (10−9-10−5 M). These results support the hypothesis that melatonin, by inhibiting the action of nitric oxide on coronary vascular smooth muscle, selectively potentiates the vasoconstrictor response to serotonin in coronary arteries with endothelium.

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