Pentobarbital Anesthesia Reduces Blood–Brain Glucose Transfer in the Rat

Abstract

Pentobarbital anesthesia (40 mg/kg) was accompanied by a 50% decrease of blood flow and a 40% decrease of unidirectional blood-brain glucose transfer in the parietal cortex of the rat brain. The correlation was explained by a decrease of the number of perfused capillaries. The maximal transport capacity, Tmax, decreased 409-235 .mu.mol 100/g min and the half-saturation Km 8.8-4.9 mM. At 8.3-8.7 mM-glucose in arterial plasma the transfer constant (clearance) for unidirectional blood-brain transfer decreased 0.195 .+-. 0.011 in awake rats to 0.132 .+-. 0.005 ml/g min in anesthetized rats. The decrease was 1/2 due to less complete diffusion-limitation of glucose uptake at the low plasma flow rate in brain and 1/2 to the decreased Tmax.