Dissociation and diurnal variation of prostaglandin E2 6-keto-prostaglandin-F1-alpha, and thromboxane B2 excretion in healthy females

The existence of diurnal variation in renal function is well described. Prostaglandins are intimately involved with renal physiology, yet a diurnal variation in their excretion is not well documented. We collected 12 consecutive 2 hour urine specimens from 10 young healthy females and measured prostaglandin E2 [PGE2], thromboxane B2 [TXB2], and 6-keto-prostaglandin-F1-alpha by radioimmunoassay for each specimen. We also measured urine volume, urine sodium, and urine creatinine levels. Regression analysis was used to determine the best sine curve for time versus each set of mean values. Only the urinary excretion of PGE2 and TXBZ, as well as water were found to significantly fit the generated sine curves. The curves for PGE2 and TXB2 showed a temporal dissociation in their peak and trough values. The excretion of PGE2 between 0800 hours and 2000 hours was significantly higher than during the hours of 2000 and 0800. The opposite was true for the TXB2 excretion. This data suggests that these two prostaglandins and water are excreted in a sine wave pattern. It also suggests that the excretion of PGE2 and TXB2 may respond to different time associated stimuli. We also showed a significant correlation between PGE2 excretion and both the excretion of water and sodium.