[Effect of verapamil on the molecular characteristics of myocardial actomyosin in experimental ischemia]. / Vliianie verapamila na molekuliarnuiu kharakteristiku aktomiozina miokarda pri éksperimental'noi ishemii.

Verapamil was shown to be able to recover a significantly depressed actomyosin ATPase activity of the unaffected left ventricular area in experimental myocardial ischemia. The drug also increased Ca-sensitivity of the ATPase reaction, with the amount of actomyosin components (Tn-1, LCM-1, LCM-2, Tn-C) almost reaching the control level. The possibility of direct interaction of verapamil with Ca-binding sites on actomyosin macromolecule is suggested. Its influence on metabolism and gene expression is not excluded.

[Effect of simulated gravitational loading on chick embryo myocardium]. / Vliianie na miokard kurinogo émbriona modelirovannoi gravitatsionnoi peregruzki.

Daily centrifugation of 5--8-day embryos at 7 G for 20 min by means of a specially designed attachment to dlHP-1 decreased the amplitude and increased the rate of rhythmic activity of ventricular myocytes, the automatic activity of atrial pacemakers remaining unaltered. These changes were accompanied by a decrease of Ca2+-sensitivity of myocytes. Daily centrifugation of 11--20-day chick embryos led to myocardial hypertrophy and increase in the diameter of myocardiocytes as well as to decrease in the content of actin, troponin-T and the second light chain of myosin, increase in the content of tropomyosin and emergence of the third light chain of myosin in the electrophoregrams. It appears that the changes in the composition of protein subunits of the contractile system are induced by selective activation of proteolytic enzymes in the muscle tissue.

[1 of the molecular factors of development of compensatory myocardial hypertrophy]. / Ob odnom iz molekuliarnykh faktorov razvitiia kompensatornoi gipertrofii miokarda.

Using the method of tryptic digestion, the authors have found that myosin of a hypertrophied myocardium is characterized by a high resistance to proteolysis. At the final stage of compensatory hypertrophy of the myocardium an increased activity of the myofibril catherpsins is discovered. According to the authors, one of the important factors of the compensatory growth of myofibrils consists in the high resistance of the newly synthesized proteins to decay. In characterizing the subunit composition and kinetics of the tryptic decay the possibility of the synthesis of a new population of myosin in the process of compensatory hypertrophy has been postulated. This demonstrates the heterogeneity of the activation of the genetic segments that control the synthesis of protein myofibril subunites with due regard to the regimen ot the myocardium work.