AJP - Renal Physiology, Vol 249, Issue 2 220-F226, Copyright © 1985 by American Physiological Society
pH regulation of endogenous acid production in subjects with chronic ketoacidosis
V. L. Hood
In a previous study of starvation-induced acute ketoacidosis, net ketoacid
production was inhibited by acid and facilitated by base ingestion. To
determine whether hydrogen ion modifies net ketoacid production during
chronic ketoacidosis, six over-weight volunteers ingested NaHCO3, NaCl, or
NH4Cl (2 mmol X kg-1 X day-1), each for 7 days, during weeks 6-8 of
ketogenic dieting. During days 4-7 of each phase, blood bicarbonate was
stable but lower in the NH4Cl (19.6 +/- 0.7 mM) than the NaHCO3 (23.7 +/-
0.7 mM) phases. Throughout these periods, acid intake differed by 216
mmol/day, whereas acid output differed by 129 mmol/day between the NaHCO3
and the NH4Cl phases. The major contribution to this difference in acid
balance was a difference in net organic acid (ketoacid) production.
Although blood ketones were stable, ketoacid excretion, reflecting net
ketoacid production, was decreased by 59% with acid and increased by 66%
with base compared with NaCl (control) ingestion. Thus, in this state of
chronic ketoacidosis, challenges to acid-base balance were countered by a
rapidly occurring, sustained, reversible, and quantitatively significant
modification of net acid production which acted as an effective mechanism
for acid-base regulation.
