EFFECTS OF POTASSIUM AND SODIUM ON RESPIRATION: THEIR SPECIFICITY TO SLICES FROM CERTAIN BRAIN REGIONS

Abstract

Brain slices and muscle differ from other tissue (e.g. kidney and peripheral nerve) in showing an increased rate of respiration during incubation in media containing high concentrations of K. The K-stimulated respiration declines rapidly both in muscle and in brain slices but follows a different course in each of the 2 preparations. A minimum concentration of Na in the medium is required to maintain the rate of O2 uptake in brain slices and in muscle during prolonged incubation. Kidney slices, in contrast, are able to maintain their respiration in a Na-free medium but at a decreased level. An increased concentration of Na in the medium causes a stimulated respiration in muscle but not in brain slices. Within the central nervous system the effects of increased K concentrations or decreased Na concentrations are limited to slices that contain grey matter from the brain. Neither white matter nor grey matter from the spinal cord shows an increased rate of 02 uptake in K -rich media or a rapid respiratory decline in Na-free media.