Role of endogenous prostaglandins in the mechanism of action of CO2 and O2 on the morphofunctional state of the capillary system in the cat cerebral cortex

: In acute experiments on cats hypocapnia produces an appreciable diminution in the mean diameter of the capillaries and an increase in the number of the non-functioning capillaries of the brain cortex. Hypercapnia and hypoxia raise the mean diameter of the capillaries. The former leads to the opening of the non-functioning capillaries whereas the latter one does not affect this indicator. Despite the fact that the indomethacin-induced inhibition of prostaglandin biosynthesis produces no effect on the morphofunctional shifts in brain microcirculation during hypocapnia it averts the effects of hypercapnia and hypoxia on the capillary diameter. An assumption is made about the heterogeneity of receptor formations in the smooth muscles of the arterioles and precapillary sphincters responding to CO2.