Myosin isoenzyme redistribution in chronic heart overload

AM Lompre, K Schwartz, A d'Albis, G Lacombe… - Nature, 1979 - nature.com
AM Lompre, K Schwartz, A d'Albis, G Lacombe, N Van Thiem, B Swynghedauw
Nature, 1979nature.com
Since the first observation by Spann et al. 1, it has become clear that in cardiac hypertrophy
induced by a mechanical overloading, the velocity of shortening of the cardiac muscle (V
max) is reduced (see ref. 2 for review). Most authors agree that this mechanical alteration is
accompanied by a decrease in the Ca2+-dependent ATPase activity of myosin (see ref. 3 for
review). The molecular basis of such changes was unknown because the structural
modifications of the myosin molecule were ill-defined4–6. Nevertheless, it has recently been …
Abstract
Since the first observation by Spann et al.1, it has become clear that in cardiac hypertrophy induced by a mechanical overloading, the velocity of shortening of the cardiac muscle (Vmax) is reduced (see ref. 2 for review). Most authors agree that this mechanical alteration is accompanied by a decrease in the Ca2+-dependent ATPase activity of myosin (see ref. 3 for review). The molecular basis of such changes was unknown because the structural modifications of the myosin molecule were ill-defined4–6. Nevertheless, it has recently been shown that, like skeletal muscle myosin7, cardiac myosin is composed of several polymorphic forms, comparable to isoenzymes8,9. In the skeletal muscle, new functional requirements can induce changes in both contractile activity and type of myosin isoenzyme synthesised10–13. We now report that an increase in cardiac work produced by mechanical overloading in rats induces the preferential synthesis of a cardiac myosin isoenzyme characterised by specific immunological and electrophoretic properties and exhibiting a lower ATPase activity. This adaptive change could account for the reduced shortening speed of this hypertrophied cardiac muscle.
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