Ziegelhoffer A, Dhalla N S
Division of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Winnipeg, Canada.
Mol Cell Biochem. 1987 Oct;77(2):135-41. doi: 10.1007/BF00221922.
Electrical stimulation of the rat heart sarcolemmal membranes with a square wave current was found to increase Ca2+-ATPase activity. This activation of the enzyme was dependent upon the voltage of the electric current, frequency of stimulation and duration of stimulation of the sarcolemmal membranes. The increase in Ca2+-ATPase was reversible upon terminating the electrical stimulation. The activation of sarcolemmal Ca2+-ATPase due to electrical stimulation was markedly depressed when the reaction was carried out at high pH (7.8 to 8.2), low pH (6.6 to 7.0), high temperatures (45 to 50 degrees C) and low temperatures (17 to 25 degrees C) of the incubation medium. Ca2+-antagonists, verapamil and D-600, unlike other types of inhibitors such as propranolol and ouabain, were found to reduce the activation of sarcolemmal Ca2+-ATPase by electrical stimulation. These results support the view that Ca2+/Mg2+ ATPase may be involved in the gating mechanism for opening Ca2+-channels in the sarcolemmal membrane upon excitation of the cardiac muscle.
研究发现，用方波电流对大鼠心脏肌膜进行电刺激可增加Ca2+-ATP酶活性。该酶的这种激活作用取决于电流电压、刺激频率以及肌膜的刺激持续时间。终止电刺激后，Ca2+-ATP酶活性的增加是可逆的。当在孵育介质的高pH值（7.8至8.2）、低pH值（6.6至7.0）、高温（45至50摄氏度）和低温（17至25摄氏度）条件下进行反应时，电刺激引起的肌膜Ca2+-ATP酶激活作用会明显受到抑制。与普萘洛尔和哇巴因等其他类型的抑制剂不同，Ca2+拮抗剂维拉帕米和D-600可降低电刺激对肌膜Ca2+-ATP酶的激活作用。这些结果支持以下观点：Ca2+/Mg2+ ATP酶可能参与了心肌兴奋时肌膜中Ca2+通道开放的门控机制。
