Enzyme histochemical studies on veno-venous grafts in rats.

To study the extent, duration, and localization of metabolic changes in vein-to-vein grafts in rats, the sequential changes in enzymatic activity of veno-venous grafts in rats were evaluated by histochemical demonstration of the activity of two oxidoreductases (lactate dehydrogenase and succinate dehydrogenase) and two hydrolytic enzymes (adenosine triphosphatase and alkaline phosphatase). All the enzymes studies showed a decrease in staining 1 day after transplantation, the change being most pronounced for AFOS in the subendothelial layer. The recovery of staining intensity was noted after 3 days, the enzyme activity reaching the pregrafting level at 1 week. Different from the previous observations on vein-to-artery grafts, these vein-to-vein grafts showed less depression of enzyme activity during the first days after transplantation, neither did they display a continuing strong activity later on, probably due to lack of a thickening intimal layer.