Effect of acute water loading on urinary excretion of prostaglandin E in hypertensive patients

To assess the relationship of urine flow to the urinary excretion of prostaglandin E (PGE), urinary excretion of PGE was measured before and after acute water loading (20 ml/kg orally) in patients with hypertension. Water loading promptly increased urinary excretion of PGE as well as urine flow rate and decreased urine osmolality (all p<0.001), but did not affect urinary excretions of sodium, potassium and creatinine, plasma renin activity and plasma aldosterone concentration. There was a significant positive correlation between urine flow rates and urinary PGE excretion rate (p<0.01). Urinary PGE concentration correlated negatively with urine flow rate when the flow was lower than 5 ml/min (p<0.01), whereas it did not change when the urine flow rate was larger than 5 ml/min. These results may support the hypothesis that urinary excretion of PGE is determined mainly by urine flow rate in the situation of water diuresis.