Nitroglycerin induced hypotension will maintain CBF in hypertensive rats.

Cerebrovascular effects of intravenous (iv) nitroglycerin (NTG) infusions were tested in four month old spontaneously hypertensive rats (SHR) and Wistar Kyoto controls (WKY). Cerebral blood flow (CBF) changes were measured during iv NTG infusion in ventilated, halothane anesthetized rats using radioactive microspheres. In control WKY rats given isotonic saline infusions instead of NTG, blood pressure and CBF did not change over 3 microsphere injections. When blood pressure was decreased to 65 and then 45 torr with iv NTG infusions, CBF was maintained or increased in both SHR and WKY. There was no difference in response between SHR and WKY. These results support other reports that NTG has direct cerebrovasodilating effects, and indicate that this action will maintain adequate CBF in hypertensive as well as normotensive subjects to pressures below 50 torr.