Calcium Kinetics in Vascular Smooth Muscle

Weiss, George B.

doi:10.1378/chest.88.4_supplement.220s

Cited by 10 publications

(8 citation statements)

References 10 publications

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“…KCI-induced contraction in smooth muscle is the result of an increased Ca influx through voltage-stimulated type-L Ca channels, (VSCs; Bolton, 1979), and is competitively and specifically inhibited by Ca antagonists (Weiss, 1981). Flecainide inhibited in a concentration-dependent manner the contractile responses induced by high K or by Ca in K-depolarized aorta, which have been used to provide a simple means of studying drugs with possible Ca entry blocking properties (Godfraind et al, 1986).…”

Section: Discussionmentioning

confidence: 99%

Effects of flecainide on isolated vascular smooth muscles of rat

Pérez‐Vizcaíno

Ding

Tamargo

1991

British J Pharmacology

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1 The inhibitory effects of flecainide were studied on contractile responses in rat isolated aortae and caudal artery and on spontaneous mechanical activity in portal vein segments.2 In rat isolated aorta flecainide, 1O-6m-5 x 10-0M, inhibited in a dose-dependent manner the contractile responses induced by high K (80mM) and noradrenaline (NA, 10-M). These inhibitory actions were observed when flecainide was added before or after the induced contractions and were similar in aortae with or without endothelium. 3 Contractile responses induced by addition of Ca to Ca-free high-K solution were also dosedependently inhibited by flecainide (IC50 = 2.5 + 0.3 x 10 -M). Moreover, flecainide inhibited the contractile responses elicited by NA in rings incubated in Ca-free solution.4 Flecainide also inhibited the spontaneous mechanical activity in portal vein segments (ICj0 = 6.5 + 0.9 x 1O 5M).5 Flecainide, 10-4M, inhibited 45Ca uptake stimulated by high K or NA without altering 45Ca uptake in resting aortae. 6 These results indicated that in rat isolated aortae, caudal arteries and portal veins, flecainide inhibited Ca entry through voltage-operated channels and NA-induced Ca uptake as well as Ca release from intracellular stores, thus decreasing the availability of intracellular free Ca required for vascular smooth muscle contraction.

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Section: Discussionmentioning

confidence: 99%

Effects of flecainide on isolated vascular smooth muscles of rat

Pérez‐Vizcaíno

Ding

Tamargo

1991

British J Pharmacology

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“…The preparations were bathed for 15 min in nominally Ca 2+ -free KrebsHenseleit solution, and then exposed for an additional 15 min to a high-K + (65.4 mM) nominally Ca 2+ -free solution (depolarizing medium) (10,11). Soon afterwards, two cumulative concentration-response curves for CaCl 2 were obtained.…”

Section: Experimental Protocolsmentioning

confidence: 99%

Calcium antagonism and the vasorelaxation of the rat aorta induced by rotundifolone

Guedes

Silva

Barbosa-Filho

et al. 2004

Braz J Med Biol Res

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The vasorelaxing activity of rotundifolone (ROT), a major constituent (63.5%) of the essential oil of Mentha x villosa, was tested in male Wistar rats (300-350 g). In isolated rat aortic rings, increasing ROT concentrations (0.3, 1, 10, 100, 300, and 500 µg/ml) inhibited the contractile effects of 1 µM phenylephrine and of 80 or 30 mM KCl (IC 50 values, reported as means ± SEM = 184 ± 6, 185 ± 3 and 188 ± 19 µg/ml, N = 6, respectively). In aortic rings pre-contracted with 1 µM phenylephrine, the smooth muscle-relaxant activity of ROT was inhibited by removal of the vascular endothelium (IC 50 value = 235 ± 7 µg/ml, N = 6). Furthermore, ROT inhibited (pD 2 = 6.04, N = 6) the CaCl 2 -induced contraction in depolarizing medium in a concentration-dependent manner. In Ca 2+ -free solution, ROT inhibited 1 µM phenylephrine-induced contraction in a concentration-dependent manner and did not modify the phasic contractile response evoked by caffeine (20 mM). In conclusion, in the present study we have shown that ROT produces an endothelium-independent vasorelaxing effect in the rat aorta. The results further indicated that in the rat aorta ROT is able to induce vasorelaxation, at least in part, by inhibiting both: a) voltage-dependent Ca 2 channels, and b) intracellular Ca 2+ release selectively due to inositol 1,4,5-triphosphate activation. Additional studies are required to elucidate the mechanisms underlying ROTinduced relaxation.

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“…Ver (1 pu) and Flu (10pM) reduced contractions to 14mM Ca2" by 94.1 + 1.7% (n = 6) and 60.0 + 4.0% (n = 6) respectively. (Weiss, 1985). Release of intracellular Ca2 + apparently mediates the fast component of NAinduced contractions of the rat aorta and this component may be selectively preserved as a transient 2.05 1.85 Discussion contraction, in the absence of extracellular Ca2 + (Yamashita et al, 1977;Heaslip & Rahwan, 1982).…”

Section: Contractions Of the Aortamentioning

confidence: 99%

“…The spontaneous phasic activity of the portal vein and contractions to KCI have both been shown to be associated with changes in membrane potential (Axelssen et al, 1967;Weston, 1978) which would be expected to activate voltage-operated channels (Weiss, 1985). Furthermore, Weston (1978) demonstrated that 1 gM NA causes significant depolarization of the rat isolated portal vein.…”

Section: Contractions In Portal Veinmentioning

confidence: 99%

A comparison of the effects of the calcium entry blockers, verapamil, diltiazem and flunarizine against contractions of the rat isolated aorta and portal vein

Marriott

1988

British J Pharmacology

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The actions of the chemically distinct calcium entry blockers, verapamil (Ver), diltiazem (Dlz) and flunarizine (Flu) have been compared in rat isolated aorta and portal vein. KCl‐induced contractions of the rat aorta depend exclusively upon extracellular Ca2+, whereas, those induced by noradrenaline (NA) rely upon Ca2+ from intra‐ and extracellular sources. The NA‐induced contraction was pharmacologically dissected under Ca2+‐free conditions revealing a contraction dependent upon intracellular Ca2+ (EGTA‐resistant response) or a low concentration of prazosin which left a contraction which was mediated by extracellular Ca2+ (prazosin‐resistant response). The portal vein produced spontaneous rhythmic contractions and a sustained contraction to NA and KCl; however, all responses appeared to depend exclusively upon extracellular Ca2+. In the aorta, contractions which might be expected to depend upon Ca2+‐entry through voltage‐operated channels (KCl‐induced contraction) showed similar sensitivities to Ver, Dlz and Flu whereas, marked differences in the sensitivity to these agents was noted against contractions which appear to depend upon Ca2+‐entry through receptor‐operated channels (prazosin‐resistant response). Only Dlz reduced contractions mediated by intracellular Ca2+ (EGTA‐resistant response). In the portal vein, Ver and Dlz caused similar pronounced reductions of spontaneous and NA or KCl‐induced contractions. In contrast, these contractions of the portal vein were unaffected by Flu except at a concentration of 10 μM. However, contractions induced by addition of Ca2+ (0–14 mM) to previously depolarized portal veins could be reduced by Flu (100 nμ‐10 μM). The present study indicates that in the rat aorta, contractions mediated by intracellular Ca2+ and depolarization or receptor‐activated Ca2+ entry can be pharmacologically dissected and that these processes show different sensitivities to calcium entry blockade. Of the agents tested, Ver displays the properties most commonly associated with an ideal calcium entry blocker. Ca2+‐activation mechanisms in the portal vein differ from those in the aorta resulting in a different spectrum of selectivity of the calcium entry blockers studied.

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Calcium Kinetics in Vascular Smooth Muscle

Cited by 10 publications

References 10 publications

Effects of flecainide on isolated vascular smooth muscles of rat

Effects of flecainide on isolated vascular smooth muscles of rat

Calcium antagonism and the vasorelaxation of the rat aorta induced by rotundifolone

A comparison of the effects of the calcium entry blockers, verapamil, diltiazem and flunarizine against contractions of the rat isolated aorta and portal vein

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