Williamson J R, Woodrow M L, Scarpa A
Recent Adv Stud Cardiac Struct Metab. 1975;5:61-71.
Studies with a sarcolemma preparation from guinea pig hearts revealed two classes of Ca2+ binding sites: high affinity sites (Km' of 16 muM) and a 10-fold greater number of low affinity sites (Km' of 800 muM). Low affinity Ca2+ binding was inhibited by ruthenium red and verapamil, suggesting that these sites are located on the external side of the membrane. However, clear-cut competition between H+ and Ca2+ could not be demonstrated with isolated sarcolemma.
高亲和力位点（米氏常数Km'为16微摩尔）和数量多10倍的低亲和力位点（米氏常数Km'为800微摩尔）。低亲和力钙离子结合受到钌红和维拉帕米的抑制，这表明这些位点位于膜的外侧。然而，在分离的肌膜上未能证实氢离子和钙离子之间有明确的竞争关系。
