Sheu S S
Department of Pharmacology, University of Rochester, School of Medicine and Dentistry, New York.
Basic Res Cardiol. 1989;84 Suppl 1:35-45. doi: 10.1007/BF02650345.
The present chapter provides experimental evidence to show that intracellular Na+ concentration regulates cardiac contractility effectively by altering intracellular Ca2+ concentration via the Na-Ca exchange. This steep coupling between the Na+ and Ca2+ electrochemical gradients implies that a change in intracellular Na+ concentration is accompanied by a concomitant change in intracellular Ca2+ concentration (and, therefore, contractility). Under the physiologic conditions, each cardiac action potential alters intracellular Na+ concentration in a dynamic manner. Therefore, Na-Ca exchange can regulate cardiac contraction from a beat-to-beat basis.
本章提供了实验证据，表明细胞内钠离子浓度通过钠钙交换改变细胞内钙离子浓度，从而有效地调节心脏收缩力。钠离子和钙离子电化学梯度之间的这种紧密耦合意味着细胞内钠离子浓度的变化伴随着细胞内钙离子浓度（进而收缩力）的相应变化。在生理条件下，每个心脏动作电位都会动态改变细胞内钠离子浓度。因此，钠钙交换可以逐搏调节心脏收缩。
