Effect of emergent and long-term adaptation to physical strength on the resistance of Ca-transporting system of myocardial sarcoplasmic reticulum

Experiments were carried out on rats adapted to physical exercise (on the next day after completion of 4, 11, 15, and 30 swimming sessions). Catalase and superoxide dismutase activities were similar in all rats. The resistance of Ca transport into sarcoplasmic reticulum to high Ca²⁺ concentrations and autooxidaton increased starting from 4 swimming sessions, and to thermal inactivation from 11 sessions; the maximum resistance was attained after 15 sessions 1.5- to 2-fold surpassing the initial level. Maximum initial rate of Ca²⁺-transport (155% of the control) was observed after 30 swimming sessions. In acute physical strength and at the initial stages of adaptation (4 swimming sessions) functional properties of myocardial Ca-transporting system were preserved under optimal conditions, but can be readily disturbed by adverse factors. Translatedfrom Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 125, No. 1, pp. 40–44, January, 1998 Original