Lactic dehydrogenase isoenzymes in the aortic wall

Abstract

Summary LDH isoenzymes were investigated by the method of electrophoresis in agar-gel and tetrazolium detection (INT or nitro-BT were used) in supernatants of the homo-genates of aortae (intima-media samples) of the followingspecies: rat, rabbit, guinea-pig, pig, cock, duck, and man. In the aortic wall of the investigated species we found marked differences in the distribution pattern of LDH isoenzymes which did not correspond to their behaviour in other organs. The relative values of the faster migrating portions in the adventitia of the human aorta were higher than in the intima or media. Ln plaques slower migrating parts were increased in comparison with the unaffected intima. A shift towards the slow migrating portions was observed with increasing in age. The pattern of LDH isoenzymes in the aortic muscle cells is rather specific and can be hardly compared with that of smooth muscles in other organs. Hormonal control of LDH isoenzymes in rat aortae is suggested from the increase of slower migrating parts in castrated and particularly in hypothyreoid animals. An opposite effect was observed after thyreoidine administration. The implications of these fmdings are discussed. The determination of isoenzymes represents a new approach to studies of the metabolism of the vascular wall. Their changes may become apparent before the ‘total’ activity of the respective en-zyme is affected.