Tanaka T, Araki R
Department of Molecular and Cellular Pharmacology, Mie University School of Medicine.
Nihon Rinsho. 1993 Jun;51(6):1453-8.
beta-Adrenoceptor stimulation decreases the calcium-sensitivity of cardiac contractile proteins through cAMP-dependent phosphorylation of troponin I and others. Agents such as alpha 1-adrenergic receptor agonists, endothelin, angiotensin II et al. that stimulate PI turnover elicit positive inotropic responses associated with increase in the calcium-sensitivity. Phorbol ester decreases the apparent sensitivity of the contractile proteins to calcium ion through the phosphorylation of troponin T and others. Myocardial contractile force may be altered by increasing or decreasing the calcium responsiveness of the myofilaments by various drugs, which change the calcium affinity of calcium-binding proteins such as troponin C and calmodulin. Moreover, we isolated a new calcium-binding protein (S100C) from porcine heart and cloned the cDNA for this protein. Modulation of intracellular calcium signaling in cardiac muscle by protein phosphorylation and drugs awaits further investigation.
β-肾上腺素能受体刺激通过肌钙蛋白I等的cAMP依赖性磷酸化降低心脏收缩蛋白的钙敏感性。刺激磷脂酰肌醇（PI）代谢的药物，如α1-肾上腺素能受体激动剂、内皮素、血管紧张素II等，引发与钙敏感性增加相关的正性肌力反应。佛波酯通过肌钙蛋白T等的磷酸化降低收缩蛋白对钙离子的表观敏感性。各种药物可通过增加或降低肌丝的钙反应性来改变心肌收缩力，这些药物会改变肌钙蛋白C和钙调蛋白等钙结合蛋白的钙亲和力。此外，我们从猪心脏中分离出一种新的钙结合蛋白（S100C）并克隆了该蛋白的cDNA。蛋白质磷酸化和药物对心肌细胞内钙信号的调节有待进一步研究。
