Cerebral blood flow autoregulation during acute ethanol intoxication in the rat

Autoregulation of cerebral blood flow (CBF) was studied in anaesthetized rats during acute ethanol intoxication (blood alcohol concentration 2.5 to 3 g/l). For each rat an autoregulation curve was determined: 8-10 CBF measurements were made over the mean arterial pressure range 129 mmHg to 20 mmHg. MAP was raised above the resting level by angiotension II infusion, then lowered by controlled haemorrhage. In control rats, CBF autoregulation was demonstrated within the MAP range 129 mmHg to 70 mmHg: at lower pressure autoregulation was inadequate and CBF fell. In ethanol intoxicated rats CBF autoregulation was demonstrated within the MAP range 129 mmHg to 50 mmHg: at lower pressure CBF fell. Although the lower limit of CBF autoregulation was thus at an MAP 20 mmHg less than in control rats, this probably reflects suppression of cerebral metabolism, rather than an effect of ethanol on CBF autoregulation per se.