Consequences of chronic K+ depletion for the ionic composition of brain, heart, skeletal muscle and cerebrospinal fluid.

Chronic dietary K+ depletion was induced in rats for up to 90 days. The treatment induced hypokalemia, moderate hypernatremia, and moderate metabolic alkalosis which was partly compensated for by a hyperproteinemic acidosis at an unchanged arterial PCO2. Whereas the K+ content of skeletal muscle was reduced to almost half its regular content, the heart muscle was much less affected and the brain K+ content was minimally reduced or not affected depending on the duration of the K+ depletion. The reduction in muscle tissue K+ content was not fully compensated for by an increase in Na+ content. Cerebrospinal fluid K+ and H+ concentrations were decreased during K+ depletion. This may explain the decreased cerebral blood flow measured during K+ depletion at an unchanged cerebral metabolic rate for glucose.