STUDIES ON DIURETICS. II. THE RELATIONSHIP BETWEEN GLOMERULAR FILTRATION RATE, PROXIMAL TUBULAR ABSORPTION OF SODIUM AND DIURETIC EFFICACY OF MERCURIALS 1

Abstract

and Leiter (2), renal plasma flow and glomerular filtration rate are characteristically low in con-gestive heart failure. These investigators infer that a reduction in the rate of delivery of sodium, chloride, and bicarbonate ions into tubules having essentially normal reabsorptive capacities favors retention of electrolyte and water. In line with this concept Weston and Escher (3) observed that patients who fail to exhibit a satisfactory diuretic response to intravenous mercurials often have exceptionally low filtration rates, and that the administration of aminophylline, which increases filtration rate, greatly enhances the diuresis. Others including Seymour (4), Briggs (5), and Sinclair-Smith (6) have expressed doubt that a reduction in filtration rate is either a constant or a significant finding in congestive failure, and have observed loss of edema without any ac-companying increase in filtration rate or renal blood flow. The difficulties in a clinical analysis of the role of reduced filtration rate in the pathogenesis of edema are evident. Chronic renal disease is often associated with congestive failure, and reduced filtration rate might in any given instance be more related to the former than to the latter. Further-more, compensation is usually reestablished slowly and recovery of capacity to excrete salt and water might be more a function of readjustment of tubu-lar absorptive capacity than of increased delivery of filtrate into the tubules. The present study on the dog was initiated with the view of establish-ing whether or not true glomerulo-tubular imbal-ance with relative overabsorption of water and salt could be induced by a reduction in glomerular filtration rate independent of changes in tubular