Effects of intravenous anesthetics on phosphatidylinositol turnover in rat cerebral cortical prisms.

Abstract

Noradrenergic pathways in the brain have been thought to be related to the site of anesthetic action. Norepinephrine (NE) in the central nervous system stimulates phosphatidylinositol (PI) turnover through alpha 1-adrenergic receptors. The present study was designed to examine the effects of intravenous anesthetics on NE-induced PI turnover in rat cerebral cortical prisms. NE-induced inositol monophosphate (IP1) formation was inhibited by droperidol (dose for 50% inhibition [ID50], 0.0258 +/- 0.00023 microM [mean +/- SE]), fentanyl (2.36 +/- 0.0017), diazepam (201 +/- 2.12), and thiamylal (231 +/- 1.94) in a dose-dependent manner, but was not affected by ketamine. Naloxone or flumazenil did not attenuate the inhibitory effect of fentanyl or diazepam on NE-induced IP1 formation. The results suggest that these effects on the PI turnover in the cortex may be related to their pharmacologic properties including the anesthetic action.