ION ASSOCIATION. III. THE EFFECT OF SULFATE INFUSION ON CALCIUM EXCRETION *†

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Abstract
Intravenous infusion of sulfate in dogs leads to a marked increase in Ca excretion. Ca excretion in relation to filtration rate was on the average 5 times greater than during comparable diuresis induced by NaCl, NaHCO3, or sucrose. Rapid sulfate infusion lead to hypocalcemia; nevertheless, hypercalciuria persisted. The changes seen were not related to comcomitant changes in plasma K or Mg concentrations, acid-base balance, osmolality, or urine pH. Protein binding of Ca in plasma was decreased, without change in protein concentration. Sulfate was nontoxic in animals in whom deficiencies of Ca, Mg, and K were prevented by adding these cations to the infusion. The data were analyzed in terms of electrostatic association between Ca and sulfate in the urine. Half of the urinary Ca was estimated to be paired with sulfate ions. Ca in this form is apparently poorly reabsorbed by the renal tubules.