[Mechanical activity of the papillary muscles of the rat heart under high altitude conditions].

Mechanical activity of isolated papillary muscles in the left ventricle of rats was studied during permanent high altitude adaptation. The main computer parameters were: maximal developing tension, force of contraction, and capacity of papillary muscles at different periods of mountain adaptation (3, 15, 30 and 45 days). On the 15th day of mountain exposure, a statistically significant increase of maximal developing tension and papillary muscles activity was observed, which remained until the 45th day. Capacity was considerably increased on the 30th--45th day of adaptation. The data suggest positive effect of high altitude hypoxia on inotropic function of intact myocardium.