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KMID : 0390119930330020187
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Journal of Pusan Medical College
1993 Volume.33 No. 2 p.187 ~ p.196
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In Vitro Effects of Calcium on Serotonin-Induced Contraction of the Cat Carotid Arteries
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Abstract
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The influences of Ca2+ upon the contractility of the isolated carotic arterial smooth muscle induced by serotonin were studied. Segmented muscle strips were prepared from the cat carotic artery, and the mechanism of serotonin-induced contraction
was
investigated using variable extracellular Ca2+ influx-blocking gents. All experiments were performed in Tris-buffered Tyrode solution which was aerated with 100% oxygen and kept at 37℃.
@ES The results obtained were follows:
@EN 1. Serotonin caused dose-dependent contraction of the carotic aterial segment. Maximal contraction was observed at 5×10E6 M serotonin concentration and KED50 was about 10-6 M.
2. In the absence f external Ca2+, serotonin-induced contraction appeared a little, but this contraction was very little as compared with 2.5 mM external Ca2+. Serotonin was able to mobilize the intracellular Ca2+.
3. When arterial segments were bathed in a solution of 4.0 mM ca2, the response to serotonin was inhibited as compared with 2.5 mM Ca2+, indicating that extracellular Ca2+ had an autoinhibitory effect of the influx of Ca2+.
4. The contraction induced by serotonin was abolished by the treatment with lanthanum, verapamil and diltiazem, which were known to be a selective Ca2+ influx-blocker.
5. Following the inhibition of contractile force by Ca2+ influx-blocker, the vascular contraction was reappeared by the addition of norepinephrine, and it was blocked by alpha-adrenergic receptor blocking agent, phenoxybenzamine.
There results suggest that serotonin-induced contraction of the cat carotid artery is the effect of both transmembrane Ca2+ influx and the mobilization of intracellualr Ca2+.
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