Metabolic and hormonal factors influencing extrarenal buffering of an acute acid load.

This study evaluates metabolic and hormonal factors influencing extrarenal buffering of an acute acid load. Phosphate deprivation of 2 weeks duration was associated with enhanced extrarenal acid buffering. The enhanced extrarenal buffering capacity of phosphate deprivation was not dependent on the presence of parathyroid glands. Parathyroid hormone administration to phosphate-deprived rats promoted a further enhancement of the buffering capacity of an acid load. Blood pH and HCO3 during acid loading were not significantly different between control and diphosphonate-treated rats and between phosphate-deprived rats and phosphate-deprived rats treated with diphosphonate. The mortality rate, however, was significantly higher in diphosphonate-treated rats than in rats not receiving the drug suggesting that diphosphonate blunts the buffering of an acid load in both control and phosphate-deprived rats. Chronic vitamin D administration and acute administration of arginine vasopressin in pharmacologic doses were associated with significant enhancement of buffering capacity as compared to control rats. Thyrocalcitonin administration to intact but not thyroparathyroidectomized rats was associated with diminished capacity to buffer an acid load. These data demonstrate that the buffering of an acute acid load is influenced by a number of dietary and hormonal factors probably acting at the level of the bone.