Muscle specific compensatory changes in the myosin ATPase activity of cold-​acclimated Rana cyanophlictis

Myosin ATPase activity in frog skeletal and cardiac muscles of control groups had pH optimums at 5.0 and 9.0 except for rectus abdominus which had a single optimum at pH 9.0. R. cyanophlyctis Were acclimated to 12° for 40-​5 days. Myosin ATPase activity for acclimated frogs had pH optimums of 5.0 for peroneus; 5.0 and 9.0 for rectus abdominus; 7.0 and 10.0 for sartorius, gracilis major, and adductor longus; and 7.0 for the other skeletal and cardiac muscles. The ratio of activities of myosin ATPase of control frogs at pH 9.0 and 7.0 varied from 1.2 for rectus abdominus to 8.0 for semimembranosus. Almost all acclimated frog muscles had a reduced ratio of myosin ATPase activity at pH 9.0​/7.0 except the deltoid. The rate-​temp. characteristics for the enzyme varied independently in muscles on acclimation