Modulation of salt appetite by lateral ventricular infusions of angiotensin II and carbachol during sodium depletion.

Infusions of angiotensin II (AII) or carbachol (CBC) into the lateral ventricles of rats which had been depleted of sodium 4 h previously with either furosemide or polyethylene glycol produced significant changes in salt appetite and sodium and water balances relative to rats infused with saline vehicle. Infusions of AII enhanced the salt appetite and led to rapid retention of both sodium and water. Infusions of CBC abolished the salt appetite and consequently did not produce any increase in sodium balance. Water intake was greater in both AII- and CBC-infused than in vehicle-infused rats and water balances increased during CBC infusion, causing severe dilution of plasma osmolality, sodium and potassium concentrations. Carbachol thus suppressed salt appetite, despite a considerable worsening of the condition of body sodium in these hypovolemic animals. Angiotensin II facilitated the appetite and this enhancement was not secondary to any natriuresis produced by AII infusions.