Assessment of metabolic activity in aortic vein grafts in rats by histochemical examination of hydrolases.

The metabolic pattern of aortic vein grafts in rats was studied by estimating histochemically the activity of the hydrolytic enzymes alfa-esterase, aminopeptidase, adenosine triphosphatase, acid phosphatase and alkaline phosphatase. The enzyme activity was lowest in the 16 hour and 1 day old grafts, and recovery was noted at three days. Five days after transplantation the enzyme activities were higher than in the non-transplanted veins. The rapid increase in enzymatic activity found in histochemical studies on wound healing was not seen in these vein grafts. At four weeks some grafts showed intimal thickening the activity of which did not exceed that of the other layers of the graft wall. At the end of the observation period of sixteen weeks most of the grafts showed intimal thickening, and this layer stained intensely especially for ATPase. The staining pattern of most of the grafts at sixteen weeks resembled that of the aortic media.