THE DISTRIBUTION OF LACTATE DEHYDROGENASE ISOZYMES IN HUMAN SKELETAL MUSCLE FIBERS

A study of the distribution of lactate dehydrogenase isozymes in single fibers from normal human skeletal muscle is presented. The fibers were classified into red, intermediate and white types on histochemical grounds and their lactate dehydrogenase isozyme content assessed by electrophoretic separation in veronal buffered agar. The results generally agreed with previous homogenate studies on animal skeletal muscle, in that the white fibers contained almost exclusively isozymes IV and V, whereas red fibers were rich in isozymes I, II and III, but IV and V also appeared indigenous to these fibers. The intermediate fibers had an isozyme pattern combining the features of red and white fibers. The metabolic implications of these findings are discussed.