Bipolar stimulation (0.5 volt, 5/sec.) of the floor of the 4th ventricle caused increased renal excretion of Na and Cl and a smaller increase in K excretion in 5 anesthetized dogs, slight changes in 3, and decreased excretion in 2. In 2 dogs, increasing the stimulus to 1 volt resulted in decreased excretion of these electrolytes.