Cerebrovascular and Metabolic Effects of SNP-induced Hypotension in Young and Aged Hypertensive Rats

Open Access
Publisher Website
Google Scholar
Abstract
Cerebral blood flow (CBF) and cerebral O2 consumption (CMRO2) were measured in young (4 mo.) and aged (24-26 mo.) spontaneously hypertensive (SHR) rats and Wistar Kyoto (WKY) controls under control anesthetized conditions (70% N2O, 30% O2) and during hypotension induced with i.v. sodium nitroprusside (SNP) infusions. CBF was measured with radioactive microspheres, and cerebral arterial-venous blood O2 measurements were determined from arterial and sagittal sinus blood samples. Arterial blood PCO2 [CO2 tension] was maintained at .apprx. 35 mm Hg and body temperature at 37.degree. C. Under control conditions blood pressure was increased in SHR, but there was no significant difference in CBF or CMRO2 between SHR and WKY or young and aged rats. CBF and CMRO2 were maintained in WKY when mean blood pressure was decreased to 65 mm Hg with SNP infusion. CBF was significantly decreased in young and aged hypertensive rats during SNP-induced hypotension. CMRO2 was also decreased in both young and aged hypertensive animals. Evidently, SNP-induced hypotension will maintain CBF and CMRO2 in normotensive subjects, but the direct cerebrovasodilating effects of SNP are moderate and will not reverse the cerebrovascular changes induced by chronic hypertension.