The action of acetylcholine and catecholamines on an intracellular calcium store in the smooth muscle cells of the guinea‐pig taenia coli.
The action of acetylcholine and catecholamines on an intracellular calcium store in the smooth muscle cells of the guinea‐pig taenia coli.
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乙酰胆碱和儿茶酚胺对豚鼠大肠杆菌平滑肌细胞内钙储存的作用。
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发表时间：
1979
期刊：
影响因子：
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通讯作者：
L. Raeymaekers
中科院分区：
文献类型：
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作者：
R. Casteels;L. Raeymaekers
1.通过记录在含有2 mM-EGTA的无钙溶液中孵育的结肠带薄条（直径100 - 150微米）的等长张力发展，研究了细胞内Ca库在兴奋-收缩偶联中的作用。2.结肠带的平滑肌细胞在暴露于富含K+和无Ca的溶液期间不收缩。然而，浓度超过10（-6）M的乙酰胆碱或卡巴胆碱可引起收缩反应。这些收缩可能是由细胞内Ca的释放引起的。钙也从同一个商店释放出来，虽然效果不太好，组胺和咖啡因。3.细胞内钙库中的钙量，如在无钙溶液中卡巴胆碱收缩的幅度所揭示的，在高（K+）0或含有低浓度卡巴胆碱的溶液诱导收缩后增加。这种收缩幅度在用高浓度卡巴胆碱刺激后降低。充满的钙库中的钙量足以产生接近最大的收缩。4. K+去极化过程中β受体的激活降低了挛缩的高度，并在无钙溶液中诱导了卡巴胆碱反应，该反应高于在无异丙肾上腺素的情况下先前K+去极化后获得的反应。这一观察结果表明，卡巴胆碱敏感性储存中Ca的摄取增加有助于β受体激动剂的舒张作用。5.在K+去极化溶液中加载了45 Ca的组织中，当用卡巴胆碱刺激肌肉时，观察到Ca释放到无Ca溶液中，但当用无Ca的高K+刺激时则没有。当异丙肾上腺素存在时，在负载45 Ca的过程中释放更大。6.从溶液中去除Na+对Ca库产生复杂且无法解释的作用。用Tris+和K+取代Na+具有类似的效果。7.可以得出结论，豚鼠结肠带的平滑肌细胞具有参与兴奋-收缩偶联的Ca的细胞内储存。该储存对毒蕈碱激动剂、β激动剂和单价离子敏感，但不受外膜去极化的影响。
1. The role of an intracellular Ca store in excitation‐contraction coupling was studied by recording isometric tension development of thin strips (100‐150 micron in diameter) of taenia coli incubated in Ca‐free solution containing 2 mM‐EGTA. 2. The smooth muscle cells of taenia coli do not contract during exposure to a K+‐rich and Ca‐free solution. However a contractile response can be elicited by acetylcholine or carbachol at concentrations exceeding 10(‐6) M. These contractions are probably induced by a release of intracellular Ca. Ca is also released from the same store, although less effectively, by histamine and caffeine. 3. The amount Ca in the intracellular store, as revealed by the magnitude of the carbachol contraction in Ca‐free solution, increases after contractions have been induced by high (K+)0 or by solutions containing low concentrations of carbachol. This contraction amplitude decreases after stimulation with a high concentration of carbachol. The amount of Ca in the filled store is sufficient for a near‐maximal contraction. 4. The activation of beta‐receptors during a K+‐depolarization reduces the height of the contracture and induces a carbachol response in Ca‐free solution which is higher than that obtained after a preceding K+ depolarization without isoprenaline. This observation indicates that an increased uptake of Ca into the carbachol‐sensitive store contributes to the relaxing effect of beta‐agonists. 5. In the tissues which have been loaded with 45Ca in a K+‐depolarizing solution, a release of Ca into Ca‐free solution is observed when the muscle is stimulated with carbachol, but not when it is stimulated with Ca‐free high K+. The release is larger when isoprenaline was present during the loading with 45Ca. 6. The removal of Na+ from the solution exerts a complex and unexplained action on the Ca store. Substitution of Na+ by Tris+ and by K+ have similar effects. 7. It is concluded that the smooth muscle cells of the guinea‐pig taenia coli have an intracellular store of Ca which participates in excitation‐contraction coupling. The store is sensitive to muscarinic agonists, beta‐agonists and monovalent ions, but is not affected by depolarization of the outer membrane.