Yeh B K, Hoffman B F
J Gen Physiol. 1968 Oct;52(4):666-81. doi: 10.1085/jgp.52.4.666.
The intracellular sodium concentration reported for young, embryonic chick hearts is extremely high and decreases progressively throughout the embryonic period, reaching a value of 43 mM immediately before hatching. This observation suggested that the ionic basis for excitation in embryonic chick heart may differ from that responsible for electrical activity of the adult organ. This hypothesis was tested by recording transmembrane resting and action potentials on hearts isolated from 6-day and 19-day chick embryos and varying the extracellular sodium and potassium concentrations. The results show that for both young and old embryonic cardiac cells the resting potential depends primarily on the extracellular potassium concentration and the amplitude and rate of rise of the action potential depend primarily on the extracellular sodium concentration.
据报道，幼龄胚胎期鸡心脏的细胞内钠浓度极高，且在整个胚胎期逐渐降低，在孵化前即刻降至43 mM。这一观察结果表明，胚胎期鸡心脏兴奋的离子基础可能与成体器官电活动的离子基础不同。通过记录从6日龄和19日龄鸡胚胎分离出的心脏的跨膜静息电位和动作电位，并改变细胞外钠和钾浓度来验证这一假设。结果表明，对于幼龄和老龄胚胎心脏细胞，静息电位主要取决于细胞外钾浓度，动作电位的幅度和上升速率主要取决于细胞外钠浓度。
