Effects of intracarotid or intraruminal injections of NaCl or NaHCO3 on sodium appetite in goats.

Goats, which have been depleted of sodium by loss of parotid saliva from a parotid fistula, have been trained to press panels with their muzzles in order to obatin small volumes of 4% (0.5 M) sodium bicarbonate to drink. Normal goats display no appetite for 4% (0.5 M) bicarbonate solutions. Goats which were depleted of sodium were highly motivated to work for bicarbonate solutions without displaying a marked fall in plasma sodium levels. It was not possible to train sodium depleted goats to press the panels to obtain intracarotid injections of 3% (0.5 M) salt solutions. The continuous intracarotid injection of concentrated 23% (3.9 M) solutions of NaCl, which increased the level of Na⁺ ions in the cephalic circulation by 11 to 18 m-equiv./1., did not reduce the rate at which sodium depleted goats pressed the panel to obtain 4% (0.5 M) bicarbonate solutions to drink. It was not possible to train sodium depleted goats to press the panel switch in order to obtain intraruminal injections of 4% (0.5 M) bicarbonate solution.