Zonal increase in lactic dehydrogenase activity in the senescent human aorta

Summary This qualitative enzyme histochemical study shows that specific lactic dehydrogenase activity increases in the ischaemic mid-medial zone of the senescent human aorta. NADH 2 -tetrazolium reductase activity decreases in this mid-medial zone, so that increased LDH activity in this layer can serve no useful purpose in electron-transfer reactions. These qualitative (slide) histochemical results confirm our previous quantitative histochemical (cytochemical) studies on the distribution of oxidative enzymes in the ageing aorta.