Carey R A, Bove A A, Coulson R L, Spann J F
Am J Physiol. 1978 Mar;234(3):H253-9. doi: 10.1152/ajpheart.1978.234.3.H253.
Cardiac muscle myosin ATPase activity is depressed and contractile function impaired when the heart is subjected to a chronic pressure overload. Administering digitalis in the presence of chronic pressure overload significantly attenuates the decline in mechanical function. The current study sought to determine if the cardiac muscle myosin ATPase activity of cats treated with digitalis in the presence of pressure overload remains normal in parallel with the mechanical function. Four groups of cats were studied: normal controls (C), animals with pressure-overload hypertrophy with or without failure (HF), normal cats that received treatment with digitalis (D), and animals that received digitalis prior to and together with pressure overload (DHF). Compared to C, the maximum myosin ATPase activity of HF was significantly (P less than 0.05) depressed, but the maximum ATPase activity of D and DHF was not altered significantly (P greater than 0.05) from C. In parallel with the enzyme maximum activity, the papillary muscle isometric rate of force development was significantly (P less than 0.005) depressed in HF compared to C; D and DHF were not significantly (P greater than 0.05) different from C. It is concluded that the depression of myosin ATPase observed in HF is not present when digitalis is administered concomitant with the pressure overload.
当心脏承受慢性压力负荷过重时，心肌肌球蛋白ATP酶活性降低，收缩功能受损。在存在慢性压力负荷过重的情况下给予洋地黄可显著减轻机械功能的下降。本研究旨在确定在压力负荷过重情况下接受洋地黄治疗的猫的心肌肌球蛋白ATP酶活性是否与机械功能一样保持正常。研究了四组猫：正常对照组（C）、有或无心力衰竭（HF）的压力负荷过重性肥大动物、接受洋地黄治疗的正常猫（D）以及在压力负荷过重之前及同时接受洋地黄治疗的动物（DHF）。与C组相比，HF组的最大肌球蛋白ATP酶活性显著降低（P<0.05），但D组和DHF组的最大ATP酶活性与C组相比无显著变化（P>0.05）。与酶的最大活性一致，与C组相比，HF组乳头肌等长力发展速率显著降低（P<0.005）；D组和DHF组与C组无显著差异（P>0.05）。结论是，在压力负荷过重的同时给予洋地黄时，未观察到HF组中出现的肌球蛋白ATP酶活性降低。
