[Physiosclerosis of various blood vessels in the rat]

The rat is notoriously resistant to atherosclerosis, however, physiosclerosis appears to develop in the rat in the same way as in man. Since physiosclerosis is very likely to set the stage for the development of atherosclerosis, there must be a fundamental difference in physiosclerosis between man and rat. In an investigation of this difference, we analyzed stress-strain curves of the aorta and determined the lipid and calcium content of several blood vessels of male Sprague-Dawley rats at various ages between 9 and 33 months. Physiosclerosis was mainly due to an increase in the amount and rigidity of collagen with no sign of early elastolysis. Lipid concentration paralleled increasing plasma level only in early senescence and decreased after an age of 18 months. Calcium obviously accumulates at the same speed as in man, dependent on the chronological rather than on the biological age. In the short-lived rat it, therefore, does not reach the high levels found in man (Fleckenstein, 1983), which may trigger changes in smooth muscle cells related to the onset of atherosclerosis.