Functional role of the potassium-induced stimulation of oxygen uptake in brain slices studied with cesium as a probe.

The potassium-induced stimulation of oxygen consumption in brain slices has a threshold value of 15-20 mM potassium, and it reaches its maximum at 35-50 mM. Although this phenomenon now has been known for almost 50 years, its physiological role remains undetermined. One reason for this may be that the high concentrations of potassium that are required for this response also have many other consequences, e.g., a depolarization of the cells, and that the different effects to some extent may mask each other. For this reason this investigation studied the effects of cesium, which evokes a maximal stimulation of oxygen consumption already at 15 mM. Like potassium, concentrations of cesium that stimulate oxygen consumption also lead to an enhanced swelling. Unlike potassium, the sodium content is affected very little by these concentrations of cesium, whereas cesium and chloride contents are increased. On this basis it is concluded that the cesium-induced stimulation of oxygen uptake is a metabolic manifestation of an active uptake of cesium and chloride, which secondarily leads to an uptake of water, i.e., the cesium-induced swelling. Analogously, it is suggested that the potassium-induced stimulation of oxygen uptake represents an active accumulation of potassium and chloride.