AJP - Endocrinology and Metabolism, Vol 239, Issue 5 328-E332, Copyright © 1980 by American Physiological Society
Effect of NH4Cl on phosphaturic response to PTH in the hamster: dissociation from acidemia
A. Hoppe, M. Destro and F. G. Knox
Previous studies indicate that the hamster fasted for 16 h fails to
demonstrate a significant phosphaturic response to parathyroid hormone
(PTH). However, when hamsters were infused with ammonium chloride, a
phosphaturic response to PTH was observed. The present studies evaluate the
respective roles of acidemia and the ammonium ion in this response. As in
previous studies, fasted thyroparathyroidectomized (TPTX) hamsters infused
with PTH showed no significant increase in the fractional excretion of
phosphate (FE rho), from 19 +/- 2 to 22 +/- 1%. Neither respiratory
acidosis (hypercapnia) nor metabolic acidosis (HCl infusion) enhanced the
phosphaturic effect of PTH, FE rho 21 +/- 4 to 20 +/- 6 and 15 +/- 2 to 16
+/- 3%, respectively. Both ammonium chloride and ammonium bicarbonate
infusions enhanced the phosphaturic response; FE rho increased from 15 +/-
5 to 27 +/- 5% (P < 0.02) and 17 +/- 3 to 25 +/- 3% (P < 0.05),
respectively. We conclude that the enhancement of the phosphaturic effect
of PTH in the fasted hamster by ammonium chloride infusions can be
dissociated from acidemia.
