Isozymic Changes in Myosin of the Cardiac Ventricular Myocardium induced by the Sympathetic Nerve.

(1)交感神经对兔心肌肌球蛋白同工酶的影响。心肌肌球蛋白有两种同工酶。α-肌球蛋白ATPase活性高，收缩快，但能量效率低。另一方面，β-肌球蛋白ATPase活性低，收缩速度慢，但能效好。交感神经完全失神经后，心室中的α肌球蛋白消失，取而代之的是β肌球蛋白。通过异丙肾上腺素兴奋β-交感神经受体，α-肌球蛋白降低，β-肌球蛋白升高。(2)充血性心力衰竭患者心肌肌球蛋白同工酶的变化，α-肌球蛋白比值与末期给药儿茶酚胺的剂量有良好的相关性。在人的心脏中，儿茶酚胺也增加了α肌球蛋白。

(1) Isozymic changes in myosin of rabbit ventricular myocardium induced by the sympathetic nerve.Cardiac myosin has two isozymes alpha and beta. alpha-myosin has high ATPase activity and its contraction is rapid but the energy efficiency is poor. On the other hand, beta-myosin has low ATPase activity, and its contraction is slow but the energy efficiency is good. After complete denervation of the sympathetic nerves, alpha myosin disappeared and was replaced by beta myosin in the cardiac ventricle. By beta sympathetic nervous receptor stimulated with isoproterenal, alpha myosin decreased and beta myosin increased.(2) Isozymic changes in myosin of the ventricular myocardium in patients with congestive heart failure.There was a good correlation between the ratio of alpha myosin and the dosage of catecholamine administered in the last stage. In the heart of human beings, also, alpha myosin was increased by catecholamine.