Isozymes of lactic dehydrogenase in skeletal muscle

¹ Departments of Physiology and Pathology, Faculty of Medicine, University of Manitoba, and St. Boniface General Hospital, Winnipeg, Manitoba, Canada

The lactic dehydrogenase (LD) isozyme patterns of red and white muscle of the guinea pig, rabbit, and mouse were examined by electrophoresis in barbiturate-buffered agar. Red muscle consistently yielded five bands of lactic dehydrogenase activity, but white muscle usually produced only two bands corresponding to isozymes IV and V. Traces of isozyme III were noted occasionally in the white muscle of the rabbit and mouse, but bands I and II were absent from the white muscle of all three species. Crystalline rabbit muscle lactic dehydrogenase produced an isozyme pattern resembling that of a mixture of red and white rabbit muscle. The lactic dehydrogenase isozyme pattern of human muscle reported by previous workers resembles that of a mixture of the red and white muscle patterns.