Ionic composition (Na+, K+, Ca+2, and Mg2+) of cerebrospinal fluid and feeding behavior in sheep

Concentrations of Na+, K+, Ca2+, and Mg2+ were measured in the cerebrospinal fluid from the lateral ventricles of hungry and satiated sheep. The concentrations of those ions and the ratios between them varied little before and after a meal. Concentrations were, in milliequivalents per litre: Na+, 156.6 +/- 1.5; K+, 2.94 +/- 0.02; Ca2+, 2.37 +/- 0.04; and Mg2+, 2.18 +/- 0.03.