Water Metabolism

Abstract

The literature of the current year contains an unusu. ally large number of reports dealing with the special problems which have arisen from the necessities of war waged on a global scale. Signifi cant additions have been made to our knowledge regarding the disturbances in fluid balance which result from such conditions as (a) extensive burns, (b) severe hemorrhage, (c) traumatic shock, (d) water and salt deprivation, and (e) exposure to extreme changes in environmental temperature and humidity� These receive special attention in the present review. Related topics, such as blood sub stitutes, renal secretion, and the special roles of proteins, electro lytes, and endocrine secretions, are dealt with as they relate to water metabolism. The general problem has been considered in two previous volumes of this publication (1,2). WATER DEPRIVATION AND DEHYDRATIONMuch of the older literature dealing with water deprivation has emphasized the effects of salt deficiency, because the usual situa tion in clinical medicine in which the subject is deprived of water is one of fasting or one in which the salt intake is deficient. Warfare on sea or land not infrequently subjects men to a',shortage of drink ing water while food is plentiful. Studies (3) have been made on men under conditions simulating the latter situation, in that they abstained from drinking water for three or four days while taking a "dry" diet which was adequate in protein, salt, and calories.There was no reduction in total plasma volume. The sodium of the serum rose while the potassium fell. The amount of urea produced by the body during the period of dehydration increased. The ex-. cretion of minerals did not keep pace with that of water, and the osmotic pressure of the plasma and of the whole body rose. This increase in osmotic pressure in dehydration may be the cause of death. Some potassium was lost from the cells, which contributed water to the extracellular compartment. The same authors (4) confirmed the findings of previous investigators (5) to the effect that the body may lose as much as 10 per cent of its weight from water deprivation without any appreciable reduction in blood 127 Annu. Rev. Physiol. 1945.7:127-162. Downloaded from www.annualreviews.org Access provided by Michigan State University Library on 02/19/15. For personal use only.Quick links to online content Further ANNUAL REVIEWS 128 McQUARRIE volume. No significant reduction in blood pressure or glomerular 'filtration rate is demonstrable during dehydration produced in this manner. Changes which characterize the urine of dehydration are due, therefore, to tubular activity alone. The effect of varying salt intake during water deprivation was found to be that of in creased plasma, which always led to a rise in urine volume, the ' , extra w�ter coming from tissue fluids (6) . On rehydration in stages, the subjects of the latter study who had been deprived of water for some' days on a diet containing five to fifteen grams of sodium chloride, showed a fall in urine volume when given some what l...

Water Metabolism

“…Ad vances in these fields have been reviewed in previous volumes (1,2) and in monographs (3). In vestigators have turned from problems of military import, such as the study of physiological stresses associated with extremes of temperature, with deprivation of water, and with trauma.…”