Swynghedauw B
Nouv Rev Fr Hematol (1978). 1982;24(3):127-9.
As a striated muscle, myocardium is characterized by a succession of contractile units, the sarcomeres, whose shortening is a consequence of the sliding of filaments. The thin filament bears the troponin-tropomyosin regulatory system. The main protein of the thick filament, myosin, is a hinge for the sliding, a receptor for actin and a catalytic site for ATP hydrolysis. This ATPase activity resulted from the combination of several isoenzyme forms of this polymer. Identification of these isoenzymes needed special precautions due to the high insolubility of myosin. The ATPase correlated with the speed of shortening as, for example, shown during chronic cardiac overload. In this condition the heart adapted to change in work by both increasing its mass and reducing its speed of shortening. The former corresponded to a stimulation of protein synthesis which affected equally myosin and actin and which was very likely a consequence of enhanced mRNA synthesis. The latter corresponded to an isoenzyme change of myosin to the benefit of the low ATPase form. This correlated with the maximal speed of shortening estimated on papillary muscle.
作为一种横纹肌，心肌的特征在于一系列收缩单位，即肌节，其缩短是细丝滑动的结果。细肌丝带有肌钙蛋白-原肌球蛋白调节系统。粗肌丝的主要蛋白质肌球蛋白，是滑动的枢纽、肌动蛋白的受体和ATP水解的催化位点。这种ATP酶活性源于该聚合物几种同工酶形式的组合。由于肌球蛋白的高不溶性，这些同工酶的鉴定需要特殊的预防措施。ATP酶与缩短速度相关，例如，在慢性心脏超负荷期间所显示的那样。在这种情况下，心脏通过增加其质量和降低其缩短速度来适应工作的变化。前者对应于蛋白质合成的刺激，这同样影响肌球蛋白和肌动蛋白，并且很可能是mRNA合成增强的结果。后者对应于肌球蛋白同工酶的变化，有利于低ATP酶形式。这与在乳头肌上估计的最大缩短速度相关。
