Local Cerebral Blood Flow, Local Cerebral Glucose Utilization, and Flow-Metabolism Coupling during Sevoflurane versus Isoflurane Anesthesia in Rats

Abstract

Compared to isoflurane, knowledge of local cerebral glucose utilization (LCGU) and local cerebral blood flow (LCBF) during sevoflurane anesthesia is limited. LCGU, LCBF, and their overall means were measured in Sprague-Dawley rats (8 groups, n = 6 each) during sevoflurane and isoflurane anesthesia, 1 and 2 MAC, and in conscious control animals (2 groups, n = 6 each) using the autoradiographic 2-[(14) C]deoxy-D-glucose and 4-iodo-N-methyl-[(14) C]antipyrine methods. During anesthesia, mean cerebral glucose utilization was decreased: control, 56 +/− 5 [micro sign]mol [middle dot] 100 g-1 [middle dot]-1; 1 MAC isoflurane, 32 +/− 4 [micro sign]mol [middle dot] 100 g-1 [middle dot] min-1 (-43%); 1 MAC sevoflurane, 37 +/− 5 [micro sign]mol [middle dot] 100 g-1 [middle dot] min-1 (-34%); 2 MAC isoflurane, 23 +/− 3 [micro sign]mol [middle dot] 100 g-1 [middle dot] min-1 (-58%); 2 MAC sevoflurane, 23 +/− 5 [micro sign]mol [middle dot] 100 g-1 [middle dot] min-1 (-59%). Local analysis showed a reduction in LCGU in the majority of the 40 brain regions analyzed. Mean cerebral blood flow was increased as follows: control, 93 +/− 8 ml [middle dot] 100 g-1 [middle dot] min-1; 1 MAC isoflurane, 119 +/− 19 ml [middle dot] 100 g-1 [middle dot] min-1 (+28%); 1 MAC sevoflurane, 104 +/− 15 ml [middle dot] 100 g-1 [middle dot] min-1 (+12%); 2 MAC isoflurane, 149 +/− 17 ml [middle dot] 100 g-1 [middle dot] min-1 (+60%); 2 MAC sevoflurane, 118 +/− 21 ml [middle dot] 100 g-1 [middle dot] min-1 (+27%). LCBF was increased in most brain structures investigated. Correlation coefficients obtained for the relationship between LCGU and LCBF were as follows: control, 0.93; 1 MAC isoflurane, 0.89; 2 MAC isoflurane, 0.71; 1 MAC sevoflurane, 0.83; 2 MAC sevoflurane, 0.59). Mean and local cerebral blood flows were lower during sevoflurane than during isoflurane anesthesia. This difference cannot be explained by differing changes in glucose utilization because glucose utilization was decreased to the same extent in both groups.