Neurohumoral mechanisms of sodium-dependent hypertension.

The contribution of neurohumoral factors to arterial pressure has been studied in several models of sodium-dependent hypertension including the deoxycorticosterone-saline, Dahl salt-sensitive rats, and reduced renal mass-saline. Observations from these animals have largely pointed to the sympathetic nervous system and arginine vasopressin (AVP) as the critical factors responsible for mediating the increased arterial pressure. Our work has indicated that the one-kidney, figure-8 renal wrap model of experimental hypertension is also sodium dependent. In these rats, prior sodium depletion prevented the development of hypertension whereas high sodium intake exacerbated the increase in arterial pressure. An activation of the sympathetic nervous system and increased AVP activity appeared to be responsible for the hypertension in rats maintained on normal and high sodium intake. Stimulation of the AVP and sympathetic nervous systems in sodium-dependent hypertension may be associated with a suppression of cardiovascular gamma-aminobutyric acid (GABA)-ergic function in the central nervous system. The inhibitory neurotransmitter, GABA, and an inhibitor of GABA uptake, nipecotic acid, lowered arterial pressure in a sodium-stimulated model of hypertension.