Changes in the properties of platelets from rats with experimentally induced shortened platelet survival

Platelet survival is shortened in experimental animals in which indwelling aortic catheters have been placed. We have examined the properties of platelets harvested from rats on day 1 or day 6 after insertion of indwelling aortic catheters. Platelets taken from these animals at 6 days (but not at 1 day) survived in normal rats or in rats with indwelling catheters for a significantly longer time than platelets from sham-operated rats. The catheters caused a persistent fall in the platelet count, an increase in the proportion of platelets in the most dense fraction after separation on discontinuous Stractan density gradients, and a decrease in mean sialic acid and protein per 10(9) platelets, but not change in modal size as determined with a Coulter Counter Channelyzer. No significant differences in the sensitivity to aggregating and release-inducing agents (ADP, thrombin, or collagen) were observed. It seems likely that chronic damage of the vessel wall shortened platelet survival and increased platelet turnover, although the increase in platelet production was not sufficient to maintain the platelet counts at the same values as in the sham-operated animals. The prolonged survival times in recipient rats of platelets from rats with indwelling aortic catheters indicate that a population of predominantly young platelets exists in these animals. Their increased density supports this conclusion.