AJP - Regulatory, Integrative and Comparative Physiology, Vol 262, Issue 2 269-R275, Copyright © 1992 by American Physiological Society
Modulation of plasma aldosterone by physiological changes in hydrogen ion concentration
G. V. Jones, B. M. Wall, H. H. Williams, D. N. Presley, D. G. Sapir and C. R. Cooke
Department of Medicine, Veterans Affairs Medical Center, Memphis, Tennessee.
To assess the effect of extracellular hydrogen ion concentration (PH+) on
aldosterone secretion, studies in which other known modulators could be
controlled were performed on 13 patients undergoing hemodialysis. High (35
mM) or low (14-17 mM) dialysate bicarbonate concentrations were utilized on
separate days to either decrease or increase PH+, while plasma potassium
concentrations (PK) were held at constant levels and changes in plasma
renin activity (PRA) were minimized by avoiding changes in body weight.
Changes in PH+ were associated with concordant changes in plasma
aldosterone concentration (Pa) in both high- and low-bicarbonate studies.
When these changes in Pa in high- and low-bicarbonate studies were analyzed
together as a function of corresponding changes in PH+, a significant
correlation could be demonstrated (r = 0.659, P less than 0.001). There was
no correlation between changes in Pa and changes in PK, plasma sodium,
plasma adrenocorticotropic hormone (ACTH), or PRA. Using the same methods
to control PH+ and other variables during hemodialysis, the effects of
altered PH+ on ACTH-stimulated aldosterone and cortisol secretion were
evaluated in studies on six patients who received incremental infusions of
ACTH after pretreatment with dexamethasone. In these studies, there was no
demonstrable effect of PH+ on Pa or plasma cortisol concentration. We
conclude that physiological changes in PH+ have a weak modulating effect on
basal aldosterone secretion that may not be evident in the presence of
other acutely applied stimuli.
