Cerebral Energy Levels during Trimethaphan-induced Hypotension in the Rat

Open Access
Publisher Website
Google Scholar
Abstract
Hypotension may be expected to produce less perturbation of metabolism in the brain when cerebral metabolic rate is lowered by deep anesthesia. Male Wistar rats having unilateral carotid-artery ligation were exposed to mean arterial pressure (MAP) of 40 torr for 20 min by an i.v. trimethaphan infusion during anesthesia with halothane, 0.6 or 2%, in oxygen. Cortical tissue metabolite levels on the side of the ligated carotid artery were more abnormal in rats receiving halothane, 0.6%, than in those receiving halothane, 2%. Values at halothane, 0.6%, were ATP, 1.71 .+-. 0.05 (.+-. SEM standard error of the mean) .mu.mol/g, phosphocreatine (PCr) 1.97 .+-. 0.07 .mu.mol/g, and lactate 16.5 .+-. 5.1 .mu.mol/g; corresponding values at halothane, 2%, were ATP 2.27 .+-. 0.02, PCr 4.02 .+-. 0.23, and lactate 4.75 .+-. 0.9 .mu.mol/g ATP and PCr values were significantly lower (P < 0.05) and the lactate value was significantly higher with halothane, 0.6%, than with halothane 2%. Cerebral O2 consumption decreased 47% in rats anesthetized with halothane, 2%. Preservation of cortical metabolite levels in deeply anesthetized animals suggests a protective effect of cerebral metabolic depression.