The Relative Importance of Calcium Influx and Efflux via Na-Ca Exchange in Cultured Myocardial Cells

摘要: In the intact myocardial cell, Ca homeostasis consists of several interrelated processes: influx across sarcolemma; uptake and release by intracellular organelles, notably sarcoplasmic reticulum mitochondria; binding to from proteins; transsarcolemmal efflux. Since work Niedergerke1 it been recognized that efflux increase with electrical activation. Voltage clamp studies have suggested some involved in activation contraction occurs via slow channel.2 This is believed trigger stored within reticulum,3 resulting a rise free-Ca ion sufficient produce myofilaments. It possible may enter cell under circumstances Na-Ca exchange carrier.4 However, relative magnitudes into channel, during normal excitation-contraction coupling, not established.