Differences in Ca2+ mobilization by muscarinic agonists in tracheal smooth muscle.
Differences in Ca2+ mobilization by muscarinic agonists in tracheal smooth muscle.
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气管平滑肌中毒蕈碱激动剂对 Ca2+ 动员的差异。
DOI：
10.1152/ajplung.1993.264.1.l53
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Gunst,SJ
中科院分区：
文献类型：
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作者：
al-Hassani,MH;Garcia,JG;Gunst,SJ
毒蕈碱激动剂乙酰胆碱 (ACh) 和 McN-A-343 可激活犬气管平滑肌中同质的 M3 受体群。然而，ACh 在刺激力量发展和主动缩短以及对抗异丙肾上腺素引起的松弛方面比 McN-A-343 更有效。在其他组织中，相同的毒蕈碱受体可能与多个亚细胞途径偶联，但根据激动剂的功效激活不同的途径。本研究探讨了不同功效的毒蕈碱激动剂对犬气管平滑肌的兴奋-收缩耦合机制。 ACh 在刺激磷酸肌醇产生方面更有效，并引起细胞内 Ca2+ 浓度 ([Ca2+]i) 的初始瞬时大幅增加，而 McN-A-343 仅引起 [Ca2+]i 缓慢逐渐增加。通过电压控制通道的细胞外 Ca2+ 流入在任一激动剂诱导的收缩中发挥次要作用。结果表明，ACh 和 McN-A-343 的收缩可能是由相同的亚细胞途径介导的；然而，ACh 刺激这些通路的能力更强，导致 Ca2+ 激活的动力学截然不同。
The muscarinic agonists acetylcholine (ACh) and McN-A-343 activate a homogeneous population of M3 receptors in canine tracheal smooth muscle. However, ACh is much more efficacious than McN-A-343 both at stimulating force development and active shortening and at antagonizing relaxation induced by isoproterenol. In other tissues, the same muscarinic receptor may be coupled to multiple subcellular pathways, but activate different pathways depending on the efficacy of the agonist. The present study investigated mechanisms of excitation-contraction coupling in canine tracheal smooth muscle by muscarinic agonists of different efficacy. ACh was more effective at stimulating inositol phosphate production and elicited a large initial transient increase in intracellular Ca2+ concentration ([Ca2+]i), whereas McN-A-343 elicited only a slow gradual rise in [Ca2+]i. Extracellular Ca2+ influx through voltage-operated channels played a minor role in contractions induced by either agonist. Results suggest that contractions by ACh and McN-A-343 may be mediated by the same subcellular pathways; however, the greater potency of ACh at stimulating those pathways results in very different kinetics of Ca2+ activation.