ACUTE REDUCTION IN EXTRACELLULAR FLUID VOLUME AND THE CONCENTRATION OF ANTIDIURETIC HORMONE IN BLOOD1

Abstract

A new chemical method for the extraction and purification of blood anti-diuretic hormone (ADH) has been applied to the study of the effect of a reduction in extracellular fluid volume on the release of ADH in the dog. The extracellular fluid volume was reduced by peritoneal lavage with a hypertonic solution. This hypertonic solution had an electrolyte composition similar to that of interstitial fluid and a glucose concentration of 10%. Twenty minutes after the start of lavage the concentration of ADH in jugular vein blood had increased six-fold. At this time there was only a relatively small reduction in extracellular fluid volume. The plasma osmolality was increased by 4% as the result of an influx of glucose from the lavage solution. However, the increased blood concentration of ADH was apparently not the result of the increased plasma osmolality. When the plasma osmolality was elevated to a similar extent by the intravenous infusion of a concentrated glucose solution, the concentration of ADH in jugular vein blood was not affected. Thus, it is concluded that acute reduction in extracellular fluid volume results in increased release of ADH by the neurohypophyseal system.