Arachidonate has a positive effect on the electrogenic sodium-potassium pump in the mouse diaphragm.

Sodium arachidonate 5 X 10(-5) mol X l-1 shortened the time course of hyperpolarization caused by the electrogenic Na+-K+ pump in intact muscle fibres in the mouse diaphragm preincubated in a K+-free physiological solution. Contrary to experiments on membrane fragments, no inhibition of the ouabain-sensitive Na+-K+ ATPase was observed. It is unlikely that the arachidonate may be identical with the endogenous "ouabain-like" substance (Bidard et al. 1984).