Effects of Time of Day, Age, and Gender on the Ability to Conserve a Water Load.
Annual rept. 15 Nov 94-1 Aug 95,
TRIPLER ARMY MEDICAL CENTER HI
Pagination or Media Count:
Seven adults, 2 women in the follicular phase or the menstrual cycle and 3 men, were studied. We intend to provide information relating to age, gender, and the phase of the menstrual cycle when the study is complete. The question addressed to date, regards the mechanism explaining the diurnal urinary response to a water load of 12 mIJkg lean boly mass. We observed a 20 greater P 0.02 diuresis in response to a water load during the daytime compared to nighttime, despite a slightly lower resting plasma osmolality Posm during the nighttime. This response appears to be due to a greater reduction P -0.03 in plasma osmolality of about 2 mOsm during the daytime compared to a slight 1 mOsmkg lower after the drink during the daytime compared to the nighttime P 0.008. Free water loss accounted for most of the diuretic response as expected, and although at this time the differences are not statistically significant, the increased cumulative urine flow appears to result from a prolonged decrease in urine osmolality and increase in free water clearance during the daytime compared to the nighttime.
- Anatomy and Physiology
- Medicine and Medical Research
- Stress Physiology