Effects of sinoaortic baroreceptor denervation on depletion-induced salt appetite

This study examined the effects of denervation of the carotid sinus and aortic arch baroreceptors on sodium depletion-induced salt appetite in rats. Depletion of extracellular fluid began with two injections of furosemide (10 mg/kg sc), 30 min apart, and removal of all ambient sodium from the cages. Water and sodium-deficient chow were available overnight. The next morning, access to 0.3 M NaCl was provided, and intakes of water and saline were measured every 30 min for 2 h and again at 24 h. Three such tests were administered. Groups of sham and sinoaortic baroreceptor-denervated (SAD) rats had equivalently negative water and sodium balances before access to saline the next morning. Sham-denervated rats drank sufficient saline in 2 h to achieve positive sodium balance and subsequently ingested sodium in excess of need for another 22 h. SAD rats drank half as much saline as sham-denervated rats by 2 and 24 h and remained in negative balance at 2 h. Sham-denervated rats increased their intakes of saline solution with repeated tests, but SAD rats did not. These findings suggest that arterial baroreceptors provide critical neural input for the normal expression of salt appetite.