Effects of arterial hypotension on brain metabolism in normotensive and spontaneously hypertensive rats

Abstract

Tbe effects of graded systemic hypotension induced by tbe combination of bleeding and trini et hap han camsylate infusion on brain metabolism were studied In normo ten sive rats (NTR) and spontaneously hypertensive rats (SHR). Metabolites snch as la ct ate, pyrurate and adenosine tripbosphate (ATP) of the brain frozen in situ were measured at the end of 1 hour of hypotension. In SHR, either cerebral lactateor the lactate/pyruvate (L/P) ratio increased rapidly and progressi vely with a concomitant decrease in ATP, when mean arterial blood pressure (MAP) fell below about 50 mm Hg. In NTR, on tbe other hand, the metabolites changed little until MAP fell to about 40 mm Hg. Metabolic derangements of the brain during profound hypotension were more marked and severe in SHR than in NTR. These results suggest that the SHR is more rulnerable to severe hypotension than NTR, probably due to hemodynamic difference of the cerebral circulation between the 2 groups. The increased cerebral vascular resistance and upward shift of cerebral autoregulation in hypertension might be responsible for this vulnerability. © 1981 American Heart Association, Inc.