Renal diurnal cycle in hydropenic man

¹ Medical Service, Veterans Administration Hospital; and Departments of Medicine and Physiology, University of Miami School of Medicine, Coral Gables, Florida

Ten hydropenic male subjects, 29–60 yr of age and without evidence of cardiovascular-renal disease, were examined with respect to renal function during the period 8:30 am-10:30 am. No infusions were given and because of the oliguric state of the subjects, the utmost care was used in emptying the bladder by catheter and air washout. The subjects remained recumbent in bed from the time of awakening until transferred by litter to the research unit, where they remained in the supine position throughout the test. The rate of sodium excretion remained essentially constant throughout the study period, an event contrary to the expected increase in sodium excretion due to the diurnal cycle and possibly related to the hydropenic state of our subjects. No evidence was obtained in these continuously recumbent subjects that a diurnal rhythm in sodium excretion extends into the mid-morning hours.