Abstract
Effect of sodium salicylate (SS) on renal handling and plasma concentration of calcium (Ca), phosphate (Pi) and magnesium (Mg) was studied in over-night fasted rats. Hypophosphatemic hypocalcemia was observed after the administration of 200 mg/kg of SS; on the other hand, hypermagnesemia was induced only with the dose of 400 mg/kg. A clearance study with the smaller dose of SS showed a decrease in urinary flow rate; however, the glomerular filtration rate remained unchanged. Reduction of urinary Ca excretion which was mainly due to a decreased filtered load was observed. On the other hand, we observed increased urinary excretion of Pi and decreased Mg excretion, which resulted from the changes in tubular reabsorption of Pi and Mg, respectively. It was concluded that the administration of SS caused 1) a hypocalcemia by the action on a tissue other than the nephron, followed by a decreased filtered load, then a reduction of urinary Ca excretion. 2) a decreased tubular reabsorption, which contributes to hypophosphatemia. 3) However, the temporary increase in tubular reabsorption of Mg makes only a small contribution to the hypermagnesemia. It was suggested that an inhibition of cyclooxygenase was not related to these effects of salicylate on renal handling of these electrolytes.
