Abstract
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 (40mEg/day) in 5 subjects increased urinary excretions of Na (p < 0.01) and dopamine. furosemide administered orally (20mg/day) in 5 subjects increased urinary excretions of Na (p < 0.05), dopamine (p < 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 (γ = 0.702, p < 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.
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