Changes in sodium appetite in cattle induced by changes in CSF sodium concentration and osmolality

Abstract

Alteration of the sodium concentration in the cerebrospinal fluid (CSF) of sheep induces reciprocal changes in sodium appetite. Similar studies have now been performed in cattle. Heifers were prepared with a unilateral parotid fistula and guide tubes were implanted in the skull for the introduction of probes into the lateral ventricles in order to sample CSF and infuse artificial CSF solutions. The cows were Na depleted by loss of saliva for 46 hr and then given free access for 2 hr to 300 mM NaCl NaHCO3 solution. Artificial CFS influtions at 1.9 ml/hr were begun one hour before Na access. In control experiments, the cows drank 26.4±1.2 l of Na solution in 2 hr, 1.2±0.2 l of water in the pre..