Vasopressor neurons in the rostral ventrolateral medulla of the rabbit.

Neurons within the rostral ventrolateral medulla oblongata project directly to the intermediolateral column in the thoracolumbar spinal cord. This paper reviews evidence obtained from experiments in the rabbit regarding the anatomical connections and physiological, pharmacological and histochemical properties of these cells. The following hypotheses are discussed: an increase in the firing rate of these neurons leads to a rise in arterial pressure due to sympathetic vasoconstriction, but does not affect respiratory or other somatomotor activity; the bulbospinal pathway originating from these neurons is an essential component of the central pathways mediating baroreceptor and other cardiovascular reflexes; these neurons receive tonic GABAergic inhibitory inputs, which are not all of baroreceptor origin; many of these bulbospinal neurons synthesize adrenalize. The possible role of adrenaline in the function of these neurons is considered.