A comparison of the effect of temperature, metabolic inhibitors and of ouabain on the electrogenic componen of the sodium pump in mammalian non-myelinated nerve fibres

Abstract

1. A comparison has been made of the effect of cooling, metabolic inhibitors and of ouabain on the electrogenic component of the sodium pump in mammalian non-myelinated nerve fibres.2. The hyperpolarization that occurs during the potassium-activated response that is obtained after a brief period of stimulation (5 sec, 30/sec) in potassium-free solution was taken as an index of the activity of the pump.3. Cooling decreased the amplitude and rate constant of decay of the potassium-activated response. The area of the response, which reflects the total amount of sodium that is extruded after activity, remained constant.4. Exposure to the metabolic inhibitors deoxy-D-glucose and cyanide also decreased the amplitude and rate constant of the response; as with cooling, the area remained relatively constant.5. Ouabain, however, reduced the amplitude without reducing the rate constant, which was even sometimes increased with small concentrations of ouabain. The area of the response always decreased therefore.6. The effects applying metabolic inhibitors are thus similar to those obtained on cooling, but differ from those of ouabain.