Properties of atrial and ventricular myosin in mammals of various size.

Myosin was isolated from atria and ventricles of adult rats, rabbits and pigs, and characterized by ATPase activities, the effects of temperature on the latter, the influence of alkaline preincubation on enzymatic activity and by electrophoretic fractionation of myosin peptides. It was shown that ventricular myosins are clearly distinguished by their ATPase activities and their response to pH and temperature, whereas atrial myosins were more similar to each other in this respect. However, the electrophoretic patterns of rat, rabbit and pig atrial myosin peptides produced by digestion with S. aureus V8 protease were different.