Mediation of the fastigial pressor response and a somatosympathetic reflex by ventral medullary neurones in the cat.

In chloralose-anaesthetized, artificially ventilated cats, the effects have been studied of inactivating neurones of the 'glycine-sensitive area' of the rostral ventrolateral medulla on evoked renal sympathetic and vasomotor responses. Glycine applied topically and bilaterally to the 'glycine-sensitive area' besides markedly lowering blood pressure and heart rate, reversibly abolished or severely attenuated both the pressor response and the renal nerve volley produced by electrical stimulation of the fastigial nucleus as well as the tibial to renal nerve somatosympathetic reflex. Bilateral radio-frequency lesions of the 'glycine-sensitive area' similarly lowered blood pressure and heart rate, blocked the fastigial pressor response and abolished renal nerve responses to fastigial nucleus or tibial nerve stimulation. Effective lesions extended greater than or equal to 1 mm deep from the medullary surface. These results are discussed with reference to the view that the 'glycine-sensitive area' contains neurones constituting a final descending bulbo-spinal pathway to preganglionic vasomotor neurones.