Mechanical activity of the gastrocnemius muscle in the albino rat under water deprivation at different temperatures

Abstract

1. 1. The mechanical activity of the gastrocnemius muscle of an anaesthetized rat was studied in situ. 2. 2. Weight loss of the animals amounted to 35 per cent in 5 days at 23°C and 70% relative humidity (r.h.), 39 per cent in 4·5 days at 30°C and 30% r.h. and 18 per cent in 10 hr at 37°C and 15% r.h. 3. 3. Muscle dry weight decreased in the rats deprived of water at 23 and 30°C only; water content of the muscle, however, decreased in all the experimental groups. 4. 4. Twitch contraction time and t 1 2 of relaxation were unaffected by water deprivation. 5. 5. Maximal tetanic tension was reduced by 10 per cent in the rats deprived of water at 23°C and by 23 per cent at 30°C, but did not change in rats deprived of water at 37°C. 6. 6. Total calculated muscular performance of the whole gastrocnemius per 100 g B.W. was reduced by 25 and 36 per cent in rats deprived of water at 23 and 30°C respectively but did not change in rats deprived of water at 37°C.