Calcium, Calcium Translocation, and Specific Calcium Antagonists

摘要: It is now almost one hundred years since Sidney Ringer (1882) described the importance of Ca2+ in maintenance frog heart contractility. Subsequent to this observation, it has been increasingly recognized that plays a critical and central role multitude biological events at both intra-and extracellular levels (Duncan, 1976; Kretsinger, 1976a; Table 1). However, distribution across cell membrane far from equilibrium, if resting potential (~-60mV) were equal equilibrium potential, then intracellular activity should be some 100-fold greater than activity. This quite clearly not so although accurate measurements free ionized concentrations have made many systems concensus evidence firmly indicates [Ca int 2+ ] < 10-7M (Baker, 1972; Blaustein, 1974; Reuter, 1973). Such low concentration accords with binding constants for those proteins whose known modulated by (pKD values ~ 6–7; 1976a,b) “trigger” functipn an increased (Heilbrunn, 1956).