Myosin ATPase in young and old mammalian myocardium: Responses to exercise in cold and thermo neutral environment

Abstract

<span style="font-size: 14.5pt;mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">Resting levels of blood lactate (La) were significantly lower at 35°C than at 25°C in the trained (Tr) rats while untrained (UTr) rats maintained higher levels. Extent of decrease in blood gl ucose (Glu) in Tr rats was lower in cold (C) than in thermo neutral (N) water in young but not in old. Training in C had no impact on young right and le ft ventricles (RY and LV). UTr old rats showed loss in LV Glu at both the temperatures. Old trainees had reduced RV Glu in C while no

<span style="font-size: 14.5pt;mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">change was observed at N. Substrate changes were concomitant with altered myosin ATPase activity. Young ventricles showed higher ATPase activity in LV than in RV, and training in C evoked elevations in RV enzyme. The results suggest that training may enhance the functional and biochemical activity in terms of higher myosin ATPase activity in, as against a C environment, and the effect is better pronounced in LV. Anaerobic condition is felt more in C as seen through elevated

<span style="font-size:14.5pt;mso-bidi-font-size:8.5pt; line-height:115%;font-family:" times="" new="" roman","serif""="">blood La ..

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