Lactic dehydrogenase activities of heart and skeletal muscle of exercised rats

¹ Research Laboratory, School of Physical Education, Washington State University, Pullman, Washington

Adult male albino rats of the Sprague-Dawley strain, with an approximate initial body weight of 340 g were exercised for 5 weeks on a training program consisting of swimming for one-half hour daily in water at 37 C. Pair-fed, nonexercised animals served as controls. All exercised animals gained less body weight than did their controls. The adrenals and heart ventricles of the exercised animals were enlarged, whereas the kidneys and gastrocnemii were smaller. Unit and total protein of the heart ventricles were greater for the exercised animals. Lactic dehydrogenase activities were determined in the heart ventricles and gastrocnemii. The activities were expressed in terms of unit, actual total, and relative total values. After exercise, the activities of the heart ventricles were increased, whereas those of the skeletal muscle were unchanged.