Salivary sodium and potassium concentrations in adrenalectomized rats

Abstract

Previous studies have shown that adrenalectomized rats have a lowered behavioral taste threshold for and consume more sodium chloride solution than do intact rats. We attempted to determine whether altered sodium and/or potassium saliva concentrations might accompany adrenalectomy and mediate these behavioral changes. Twenty-two rats, eleven intact and eleven adrenalectomized, were anesthetized with ether and injected with pilocarpine (7.5 mg/kg body wt): whole saliva was collected for 10 mins. The intact animals produced 0.577 ± 0.189 ml of saliva while the operated animals produced significantly less, 0.329 ± 0.204 ml. The salivary sodium concentration was 43.6 ± 13.0 meq/liter in operated rats and significantly lower, 32.5 ± 4.3 meq/liter in intact animals. There were no significant differences in potassium concentration, but the sodium/potassium ratio was significantly greater in adrenalectomized than control animals. Adrenalectomized rats secreted 14.3 meq of sodium in the 10-min period compared to 18.7 meq by the controls, suggesting that the amount of sodium per unit time in the adrenalectomized animal's oral cavity was markedly decreased. It thus seems that although the sodium concentration is higher in the adrenalectomized animal, much of this difference is accounted for by a decreased flow rate even with equivalent pharmacologic stimulation.