Study of the interrelationship between dopaminergic activity and potassium ion

The present study was designed to examine the interrelationship between dopaminergic neuron activity and potassium ion in the normotensive elderly subjects with a stable physical condition. Potassium chloride loaded intravenously (40mEq/day) in 5 subjects increased urinary excretions of Na (p less than 0.01) and dopamine. Furosemide administered orally (20mg/day) in 5 subjects increased urinary excretions of Na (p less than 0.05), dopamine (p less than 0.01) and K. Spironolactone administered orally (75mg/day) in 5 subjects brought an increase of urinary excretion of Na and a decrease of urinary excretions of K and dopamine, although these changes were not statistically significant. Metoclopramide, a dopamine antagonist, administered orally (15mg/day) in 5 subjects brought about a tendency of decrease in urinary excretions of Na and K. Between urinary amounts of K and dopamine, a positive correlation (gamma = 0.702, p less than 0.001, n = 22) was recognized. From these results, the change of the excretion of dopamine seemed to be parallel with that of K, and therefore it is suggested that a mechanism involved in the excretion of dopamine into the urine has a close relationship with that excreting K. The possible mechanisms are discussed.