1. The effect of sodium chloride-containing solution (saline) infusion on sodium excretion has been investigated in kidneys transplanted from donors into the neck vessels of other dogs (perfusors). The dogs (perfusors and donors) had been given sodium-enriched or sodium-poor diets (‘loaded’ and ‘deprived’ dogs). 2. Three series of experiments were performed: (A) loaded perfusor, loaded donor; (B) deprived perfusor, deprived donor; (C) deprived perfusor, loaded donor. 3. Kidneys from deprived dogs, transplanted into deprived perfusors, excreted less sodium after intravenous saline than kidneys from loaded dogs transplanted into loaded perfusors. However, the sodium excretion from the kidneys of loaded dogs transplanted into deprived perfusors was the same as that from the kidneys of loaded dogs transplanted into loaded perfusors. These differences suggest that intrarenal mechanisms are involved in the changes in sodium excretion which follow changes in dietary sodium balance. 4. The intrarenal mechanisms included changes in glomerular filtration rate and fractional sodium reabsorption, but not changes in filtration fraction or renin release.
1. When angiotensin II was infused into forty unselected subjects a linear relationship was found between the increment of diastolic blood pressure and the logarithm of the rate of infusion of angiotensin II. 2. The slope of this line was very reproducible on repeated determinations in the same subject. 3. When the correlations between pre-infusion plasma renin activity and various functions derived from dose—response curves were determined, it was observed that: (i) the significance of the correlation became progressively stronger when increasing thresholds of the pressor response to angiotensin II were considered; (ii) the best correlation was achieved when the slopes of the individual dose—response curves were plotted against the logarithm of corresponding plasma renin activities. 4. These results suggest that the slope of the pressor dose—response curve is the most reliable index of responsiveness to intravenously infused angiotensin II and that it may provide a satisfactory guide to the basal plasma renin activity.