Changes of metabolism during experimentally induced myotonia of rats: I. Alterations in lactate and malate dehydrogenase isoenzyme activities

Abstract

Myotonia was induced by administration of 2,4-D ip. After 2 weeks' treatment, the changes in total LDH and MDH activities and their isoenzyme patterns were investigated in muscles of different function and metabolism. To summarize the results, it might be said that in myotonia induced by 2,4-D the metabolism shifts to an anaerobic one in skeletal muscles. The relative hypoxia developing during this period switches on the regulative processes by which tissues acquire an additional possibility for the production of the energy necessary for their function. This was demonstrated by the relative increase in LDH-5 activity. Changes occurring in the heart muscle may be considered as secondary effects which may be due partly to an increased lactate level in the blood, and partly to the toxic effect of 2,4-D.