NATRIURETIC RESPONSE TO ACUTE SODIUM-CHLORIDE OR SODIUM-BICARBONATE INFUSIONS IN HUMANS

We compared the natriuretic responses to acute sodium chloride or sodi um bicarbonate loading. 2.25 mEq/kg of sodium as sodium chloride, or s odium bicarbonate was infused intravenously in 1 h. Sodium chloride in fusion resulted in a gradual increase in urinary sodium excretion (UNa V) for 4 h after starting the infusion, while sodium bicarbonate infus ion caused a transient increase in UNaV for the first 2 h followed by a decrease. The amount of sodium excreted over 4 h in the sodium chlor ide and sodium bicarbonate groups were 20.7 +/- 4.7 and 34.8 +/- 2.3% of the sodium loaded, respectively (p < 0.05). This difference could n ot be ascribed to divergent responses in glomerular filtration rate, a ldosterone, atrial natriuretic peptide, or serum albumin concentration . The difference in UNaV might be caused by the differences in renal t ubular handling of chloride and bicarbonate.