Lactate Dehydrogenase Isoenzymes in Transected Nerves.

THE recent interest in organ-specific patterns of lactate dehydrogenase (LDH) isoenzymes (WIELAND and PFLEIDERER, 1957; WROBLEWSKI, Ross and GREGORY, 1960; PLAGEMANN, GREGORY and WROBLEWSKI, 1960; WROBLEWSKI and GREGORY, 1961) stimulated search for isoenzyme pattern differences among regions of the brain. VAN DER HELM (1962) found no isoenzymic differences among several regions of the human brain. LOWENTHAL, VAN SANDE and KARCHER (1961, 1962) observed very similar patterns of LDH isoenzymes in grey and white matter, but they observed three different patterns among 15 regions in the brains of man and cat; similar data were obtained by BONAVITA and GUARNERI (1963). LOWENTHAL and co-workers also reported that the LDH isoenzyme patterns in birds and fish were markedly different than those in mammals. PFLEIDERER and WACHSMUTH (1961) described differences between cerebellar and cerebral LDH isoenzyme patterns. Marked changes of isoenzyme patterns were noted during development of the brain (FLEXNER, FLEXNER, ROBERTS and DE LA HABA, 1960; PFLEIDERER and WACHSMUTH, 1961; BONAVITA, PONTE and AMORE, 1962; GERHARDT, CLAUSEN and ANDERSON, 1963). This paper reports on the different isoenzyme patterns in the following samples of cat sciatic nerve: (1) the proximal stump of a transected nerve in which most of the enzyme was in swollen axon stumps, (2) a segment of nerve proximal to the first sample, containing no swollen axons, and in which the enzyme was distributed mostly in Schwann cells, (3) a segment of the distal part of the transected nerve in which nearly all of the enzyme was in proliferating Schwann cells, and (4) a sample of the normal contralateral nerve. We also give a simplified method for separation and measurement of isoenzyme fractions; this method, in our hands, was faster and gave better results than several other methods tested.