Vasomotor neurons in the rostral ventrolateral medulla are organized topographically with respect to type of vascular bed but not body region.

Microinjections of sodium glutamate (200-800 pmol) were made into sites within the rostral ventrolateral medulla of anaesthetized cats in which the adrenal glands had been removed and the baroreceptors denervated, while arterial pressure, renal sympathetic nerve activity and hindlimb and forelimb blood flows were measured. Hindlimb and forelimb vascular resistances were affected in a parallel fashion by injections at different sites, but there was a clear dissociation between evoked changes in renal nerve activity and either forelimb or hindlimb vascular resistance. The results indicate that ventrolateral medullary vasomotor neurons are organized topographically with respect to the type, rather than body position, of the vascular beds they control.