scholarly journals The Vasorelaxant Effect ofp-Cymene in Rat Aorta Involves Potassium Channels

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Martapolyana T. M. Silva ◽  
Fernanda P. R. A. Ribeiro ◽  
Maria Alice M. B. Medeiros ◽  
Pedrita A. Sampaio ◽  
Yonara M. S. Silva ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Potassium Channels ◽  
Vascular Smooth Muscle ◽  
Channel Blocker ◽  
Antimicrobial Activities ◽  
Rat Aorta ◽  
Relaxant Effect ◽  
Vasorelaxant Effect ◽  
Dose Dependent ◽  
Relaxing Effect

The monoterpenes are the main constituents of most essential oils andp-cymene is a monoterpene commonly found in various species of aromatic herbs, which has been reported for anti-inflammatory, antinociceptive, and antimicrobial activities. However, there is no report concerning its pharmacological activity on the vascular smooth muscle. The aim of current work was to investigate the effects ofp-cymene in isolated rat aorta and also study its mechanism of action. In this work, we show thatp-cymene has a relaxant effect, in a dose-dependent way, on the vascular smooth muscle, regardless of the presence of the endothelium. Using a nonselective potassium channel blocker, the CsCl, the relaxant effect ofp-cymene was attenuated. In the presence of more selective potassium channels blockers, such as TEA or 4-AP, no change in the relaxant effect ofp-cymene was evidenced, indicating thatBKCaandKVchannels are not involved in that relaxant effect. However, in the presence of glibenclamide or BaCl2,KATPandKirblockers, respectively, the relaxant effect ofp-cymene was attenuated. The data presented indicate thatp-cymene has a relaxing effect on rat aorta, regardless of the endothelium, but with the participation of theKATPandKirchannels.

scholarly journals Effect ofCymbopogon citratusand Citral on Vascular Smooth Muscle of the Isolated Thoracic Rat Aorta

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
R. Chitra Devi ◽  
S. M. Sim ◽  
R. Ismail
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Relaxation Effect ◽  
Rat Aorta ◽  
Major Constituent ◽  
Protective Properties ◽  
Relaxant Effect ◽  
Vasorelaxant Effect ◽  
Methanolic Extracts ◽  
Dose Dependent

Cymbopogon citratushas been shown to have antioxidant, antimicrobial, antispasmodic and chemo-protective properties. Citral, is the major constituent ofC. citratus. This study investigated the effects of methanolic extracts of leaves (LE), stems (SE), and roots (RE) ofC. citratusand citral on vascular smooth muscle and explored their possible mechanisms of action. The experiment was conducted using isolated tissue preparations, where citral, LE, SE, and RE were added separately into a tissue bath that contained aortic rings, which were pre-contracted with phenylephrine (PE). Citral, LE, and RE exhibited a dose-dependent relaxant effect on the PE-induced contractions. Citral appeared to partially act via NO as its vasorelaxant effect was attenuated by L-NAME. However, the effect of LE may involve prostacyclin as indomethacin reversed the relaxant effect of LE on the PE-induced contraction. Furthermore, citral, LE, and RE abolished the restoration of PE-induced contraction caused by the addition of increasing doses of calcium in both endothelium intact and denuded rings. These findings suggest that the relaxation effect of citral, LE, and RE is endothelium-independent and may be mainly by affecting the intracellular concentration of calcium. Citral may partially act through the NO pathway while a vasodilator prostaglandin may mediate the effect of LE.

Nickel inhibits endothelin-induced contractions of vascular smooth muscle

1990 ◽  
Vol 258 (6) ◽  
pp. C1025-C1030 ◽  
Author(s):  
K. Blackburn ◽  
R. F. Highsmith
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Isometric Force ◽  
Inhibitory Effect ◽  
Rat Aorta ◽  
Porcine Coronary Artery ◽  
Force Development ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Dose Dependent

Endothelin (ET)-induced contractions of vascular smooth muscle (VSM) are dependent on extracellular Ca2+ yet display only partial sensitivity to L-type Ca2+ antagonists. The purpose of this study was to evaluate the effect of nickel (Ni2+), a Ca2+ channel antagonist with clearly documented differential potency toward L- vs. T-type Ca2+ currents on ET-mediated contractions in VSM. Treatment of rings of left anterior descending porcine coronary artery (LAD) with Ni2+ produced a profound dose-dependent inhibition of isometric force development in response to porcine ET (ET-1). At a concentration of 360 microM, Ni2+ exerted a significant inhibitory effect on contracture in response to doses of ET-1 ranging from 3 to 100 nM. In contrast, the same concentration of Ni2+ failed to significantly affect peak force development in response to KCl depolarization (5-77 mM) or to phenylephrine (0.3-30 mM). In addition, 360 microM Ni2+ significantly inhibited the contractile response of rat aorta to 10 nM ET-1. We conclude that ET-1 activates a Ni2(+)-sensitive process in VSM which may signal an additional Ca2+ influx pathway that appears to be functionally distinct from the L-type Ca2+ channel.

scholarly journals EVALUATION OF IN-VITRO VASORELAXANT EFFECT (POTENTIAL ANTIHYPERTENSIVE) OF KIGELIA AFRICANA FRUIT METHANOL EXTRACT ON POTASSIUM CHLORIDE AND PHENYLEPHRINE INDUCED TENSION IN WISTAR RAT AORTA

2020 ◽  
Vol 4 (3) ◽  
pp. 470-475
Author(s):  
A. O. Isah ◽  
M. Idu ◽  
A. A. Abdulrahman ◽  
F. Amaechina
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Potassium Chloride ◽  
Methanol Extract ◽  
Muscle Relaxation ◽  
Rat Aorta ◽  
Smooth Muscle Relaxation ◽  
Organ Bath ◽  
Vasorelaxant Effect

This research on Kigelia africana was conducted in order to ascertain its ability to relax excited vascular smooth muscle in rat aorta. Preliminary investigation on whether the plant exhibits antihypertensive property was done before the evaluation of in vitro vasorelaxant effect. The vasorelaxant activity was determined using in vitro method on rat aorta with the aid of perfusion apparatus with a detachable organ bath. The administration of potassium chloride (KCl) raised the tension from 1.0 to 1.31 indicating that the aorta got to its peak of contraction. At 10 and 20mg/kg, the tension dropped significantly, showing relaxation of the smooth muscle while at 5mg/kg, drop in tension was insignificant at p˂0.05. However, at some of the doses, towards the end of experiment, there was steady resurge in tension showing that the aorta resumed contraction. On the application of phenylephrine (PE), the tension rose to 1.18g. On administration of the extract, the tension dropped slightly showing mild vascular smooth muscle relaxation. From the results obtained, there was seeming similarity in the action of the K. africana compared to amlodipine/Ramipril in KCl and PE induced tension in aorta respectively. However, at 10 and 20mg/kg, a substantial decrease in tension was noted indicating that the extract action is dose dependent. Thus, from this in-vitro smooth muscle relaxation study in rats, the methanol extract of K. africana has depressant property that was likely expressed by enhancing the closing of voltage operated calcium channel and ACE inhibiting activity in KCl and Phenylephrine induced tension respectively.

Impact of α1-adrenoceptor expression on contractile properties of vascular smooth muscle cells

2007 ◽  
Vol 293 (3) ◽  
pp. R1215-R1221 ◽  
Author(s):  
Adrian Gericke ◽  
Peter Martinka ◽  
Irina Nazarenko ◽  
Pontus B. Persson ◽  
Andreas Patzak
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Low Frequency ◽  
Rat Aorta ◽  
Contractile Properties ◽  
Isolated Cells ◽  
Functional Studies ◽  
Sympathetic Modulation ◽  
Dose Dependent ◽  
Subtype Distribution

Low-frequency blood pressure oscillations (Mayer waves) are discussed as a marker for sympathetic modulation of vascular tone. However, the factors that determine the frequency response of the vasculature to sympathetic stimuli are not fully understood. Possible mechanisms include functions related to α1-adrenergic receptors (α1-AR) and postreceptor processes involved in the vascular contractile response. The purpose of the present study was to examine the hypothesis that expression levels of α1-AR and their subtype distribution determine velocity and magnitude of α1-AR-mediated vascular smooth muscle cell (VSMC) contraction. α1A-, α1B-, and α1D-AR subtypes were transfected into VSMCs from rat aorta and characterized immunocytochemically via confocal microscopy. Functional studies in isolated cells were performed using video microscopy. The α1-AR agonist phenylephrine produced dose-dependent contractions of VSMCs. All transfected groups were more sensitive to phenylephrine compared with controls. Maximal contraction velocity almost doubled in transfected cells. However, no differences in observed parameters were found between the three transfected groups. Contractile properties in response to membrane depolarization with KCl were similar in all groups. In conclusion, α1-AR density determines velocity and sensitivity of α1-AR-mediated contraction in VSMCs. α1-AR subtype distribution does not appear to influence vasoconstriction to sympathetic stimuli.

Mechanisms of Direct Inhibitory Action of Isoflurane on Vascular Smooth Muscle of Mesenteric Resistance Arteries

2003 ◽  
Vol 99 (3) ◽  
pp. 666-677 ◽  
Author(s):  
Takashi Akata ◽  
Tomoo Kanna ◽  
Jun Yoshino ◽  
Shosuke Takahashi
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Vascular Reactivity ◽  
Channel Blocker ◽  
Isometric Force ◽  
Systemic Resistance ◽  
Resistance Arteries ◽  
Voltage Gated ◽  
Fura 2 ◽  
Force Relation

Background Isoflurane has been shown to directly inhibit vascular reactivity. However, less information is available regarding its underlying mechanisms in systemic resistance arteries. Methods Endothelium-denuded smooth muscle strips were prepared from rat mesenteric resistance arteries. Isometric force and intracellular Ca2+ concentration ([Ca2+]i) were measured simultaneously in the fura-2-loaded strips, whereas only the force was measured in the beta-escin membrane-permeabilized strips. Results Isoflurane (3-5%) inhibited the increases in both [Ca2+]i and force induced by either norepinephrine (0.5 microM) or KCl (40 mM). These inhibitions were similarly observed after depletion of intracellular Ca2+ stores by ryanodine. Regardless of the presence of ryanodine, after washout of isoflurane, its inhibition of the norepinephrine response (both [Ca2+]i and force) was significantly prolonged, whereas that of the KCl response was quickly restored. In the ryanodine-treated strips, the norepinephrine- and KCl-induced increases in [Ca2+]i were both eliminated by nifedipine, a voltage-gated Ca2+ channel blocker, whereas only the former was inhibited by niflumic acid, a Ca2+-activated Cl- channel blocker. Isoflurane caused a rightward shift of the Ca2+-force relation only in the fura-2-loaded strips but not in the beta-escin-permeabilized strips. Conclusions In mesenteric resistance arteries, isoflurane depresses vascular smooth muscle reactivity by directly inhibiting both Ca2+ mobilization and myofilament Ca2+ sensitivity. Isoflurane inhibits both norepinephrine- and KCl-induced voltage-gated Ca2+ influx. During stimulation with norepinephrine, isoflurane may prevent activation of Ca2+-activated Cl- channels and thereby inhibit voltage-gated Ca2+ influx in a prolonged manner. The presence of the plasma membrane appears essential for its inhibition of the myofilament Ca2+ sensitivity.

scholarly journals The Functional Availability of Arterial Kv7 Channels Is Suppressed Considerably by Large-Conductance Calcium-Activated Potassium Channels in 2- to 3-Month Old but Not in 10- to 15-Day Old Rats

2020 ◽  
Vol 11 ◽  
Author(s):  
Dongyu Ma ◽  
Dina Gaynullina ◽  
Nadine Schmidt ◽  
Mitko Mladenov ◽  
Rudolf Schubert
Keyword(s):  
Smooth Muscle ◽  
Potassium Channels ◽  
Vascular Smooth Muscle ◽  
Bk Channels ◽  
Similar Degree ◽  
Functional Impact ◽  
Adult Rat ◽  
Kv7 Channels ◽  
Contractile Effect ◽  
Arterial Contractility

BackgroundVoltage-gated potassium (Kv) channels, especially Kv7 channels, are major potassium channels identified in vascular smooth muscle cells with a great, albeit differential functional impact in various vessels. Vascular smooth muscle Kv7 channels always coexist with other K channels, in particular with BK channels. BK channels differ in the extent to which they influence vascular contractility. Whether this difference also causes the variability in the functional impact of Kv7 channels is unknown. Therefore, this study addressed the hypothesis that the functional impact of Kv7 channels depends on BK channels.Experimental ApproachExperiments were performed on young and adult rat gracilis and saphenous arteries using real-time PCR as well as pressure and wire myography.Key ResultsSeveral subfamily members of Kv7 (KCNQ) and BK channels were expressed in saphenous and gracilis arteries: the highest expression was observed for BKα, BKβ1 and KCNQ4. Arterial contractility was assessed with methoxamine-induced contractions and pressure-induced myogenic responses. In vessels of adult rats, inhibition of Kv7 channels or BK channels by XE991 or IBTX, respectively enhanced arterial contractility to a similar degree, whereas activation of Kv7 channels or BK channels by retigabine or NS19504, respectively reduced arterial contractility to a similar degree. Further, IBTX increased both the contractile effect of XE991 and the anticontractile effect of retigabine, whereas NS19504 reduced the effect of retigabine and impaired the effect of XE991. In vessels of young rats, inhibition of Kv7 channels by XE991 enhanced arterial contractility much stronger than inhibition of BK channels by IBTX, whereas activation of Kv7 by retigabine reduced arterial contractility to a greater extent than activation of BK channels by NS19504. Further, IBTX increased the anticontractile effect of retigabine but not the contractile effect of XE991, whereas NS19504 reduced the effect of retigabine and impaired the effect of XE991.ConclusionKv7 and BK channels are expressed in young and adult rat arteries and function as negative feedback modulators in the regulation of contractility of these arteries. Importantly, BK channels govern the extent of functional impact of Kv7 channels. This effect depends on the relationship between the functional activities of BK and Kv7 channels.

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