EFFECT OF INTRAVENOUS SODIUM SULFATE ON RENAL EXCRETION IN THE DOG

Abstract

During steady intraven. infusions of solns. of sodium sulfate in dogs, it was found that equality of intake and output (isorrhea) of Na and of sulfate can be reached within 3 hrs. and maintained. A minimal isorrheic quantity (MIQ) for these ions is ca. 50[mu]Eq./min. No limiting isorrheic quantity (LIQ) was found. A minimal isorrheic concn. (MIC) for Na and for sulfate was estimated at 50 mEq./l.; a limiting isorrheic concn. (LIC) for Na was estimated at 420 mEq./l.; and an LIC for sulfate was estimated at 480 mEq./l. Maximum urinary concns. (MUC) for Na and for sulfate were found at 530 and 800 mEq./l., respectively. The velocity constant of excretion for sulfate exceeds that for Na when sodium sulfate is infused, e.g., [gamma]Na = 0.0212; [gamma]SO4 = 0.0317. These values are more than 20 times greater than[gamma]Na or Cl when NaCl is infused. It is suggested that high threshold ions in the body may have a low threshold fraction, e.g., that fraction of Na which is or could be electroneutralized by sulfate. The fact that isotonic sulfate behaves diuretically like plain water, as contrasted with isotonic NaCl, is discussed in the light of the posterior pituitary hypothesis of diuresis. Evidence is presented that hypotheses which purport to account for certain phenomena in renal physiology by reference to "dominant" ions such as Na, are too simple to account for known facts. A steady state equation can be used to describe the isorrhea of sodium sulfate under the conditions of these expts. The effect of infusions of sodium sulfate on renal excretion of several ions, and on their serum levels, is reported.