Journal of Smooth Muscle Research
Online ISSN : 1884-8796
Print ISSN : 0916-8737
ISSN-L : 0916-8737
Caffeine-induced contraction of rat portal vein and effects of K-depolarization, Na-removal and low temperature
K. SHIMAMURAK. MORIYAMAS. SUNANO
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1991 Volume 27 Issue 2 Pages 75-85

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Abstract
Contribution of Ca influx from extracellular pool and Ca-release from store sites in caffeine-induced contraction of rat portal vein longitudinal muscle were examined. At 37°C caffeine induced a phasic contraction and the contraction was inhibited by verapamil or in the absence of Ca. Under low temperature, it was not decreased remarkably by verapamil or by the removal of extracellular Ca. Na-removal potentiated caffeine-induced contraction in the absence of Ca. Caffeine-induced contraction was also potentiated by high-Kdepolarization. These contractions were at both temperature inhibited greatly by ryanodine. Caffeine induced the burst of the action potential at 37°C but it was not remarkable at 17°C. These results indicate that both extracellular Ca influx and release of stored Ca are involved in the caffeine-induced contraction. However, dependence of the contraction on Ca sources are influenced by temperature, extracellular Na and membrane potential.
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この記事はクリエイティブ・コモンズ [表示 - 非営利 - 改変禁止 4.0 国際]ライセンスの下に提供されています。
https://creativecommons.org/licenses/by-nc-nd/4.0/deed.ja
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