Reticulospinal vasomotor neurones in decerebrate rats: effect of pentobarbitone.

The pattern of discharge of rostroventrolateral 'vasomotor' neurones has been studied in the decerebrate rat before and following the administration of pentobarbitone. Baroreflex inputs were effective in both situations, but the sensitivity of the reflex was heightened in the anaesthetised decerebrate condition even though the anaesthetic depressed neuronal discharge. The application of this anaesthetic failed to depress the inhibitory action of iontophoretically applied gamma-aminobutyric acid whose effectiveness was, if anything, enhanced. Arterial blood pressure was also reduced on the administration of the anaesthetic. These observations, taken together, suggest that the action of this, and potentially other anaesthetic agents, in lowering blood pressure may be mediated, in part, by the lowering of activity of these rostroventrolateral 'vasomotor' neurones.