Prostacyclin and prostaglandin synthesis in rat brain microvessels: characteristic changes in hypoxaemia.

The effects of hypoxaemia on the synthesis of prostacyclin and prostaglandins in the cerebral microvessels and on the ultrastructure of brain cortex capillaries were investigated in three groups of rats. Series I: rat embryos were kept in hypoxic-hypobaric condition for 42 hours. It resulted in the enhancement of synthesis of PG2alfa and PGE2 even two months after birth. The fine structure of the capillary endothelium remained without any pathological change. Series II: adult male rats were on hypoxic-hypobaric environment for 42 hours. There was a slight increase in the synthesis of PGE2 and PGD2 while the ultrastructure of brain capillaries was found to be normal. Series III: the hypoxic-hypobaric condition lasted for 240 hours in adult male rats. This long term hypoxaemia affected greatly the prostaglandin synthesis of brain cortex capillaries and resulted in changes in the fine structure of brain microvessels as well. The possible molecular mechanism activated by hypoxaemia in brain capillaries is discussed.