[Interrelationship between biochemical and physiological indices of skeletal muscles in the frog Rana temporaria].

Studies have been made on temporal characteristics of contraction and Mg-ATPase activity of the sarcoplasmic reticulum in various phasic and tonic muscles of the frog. The time of isometric tetanic contraction and Mg-ATPase activity of the reticulum in the phasic m. sartorius and the tonic m. coracoradialis are correlated. The data obtained suggest that the duration of twitch isometric contraction is related to calcium content of muscles.