AJP - Renal Physiology, Vol 253, Issue 3 495-F499, Copyright © 1987 by American Physiological Society
Effect of adrenalectomy on NEM-sensitive ATPase along rat nephron and on urinary acidification
C. Khadouri, S. Marsy, C. Barlet-Bas and A. Doucet
An N-ethyl-maleimide (NEM)-sensitive ATPase that displays the properties of
an electrogenic proton pump has been described in the different segments of
the rat nephron where it mediates part of the active tubular proton
secretion. Because corticosteroids are known to control kidney
acidification, we evaluated whether or not NEM-sensitive ATPase is a target
of corticosteroids in some nephron segments. For this purpose we measured
NEM-sensitive ATPase activity in the different segments of nephron
microdissected from normal and adrenalectomized rats. Results indicate that
within 1 wk after adrenalectomy NEM-sensitive ATPase activity was markedly
decreased in both cortical and outer medullary portions of the collecting
tubule (cortex, from 398 +/- 12 (+/-SE) to 145 +/- 20; outer medulla, from
293 +/- 21 to 112 +/- 14 pmol X mm-1 X h-1); however, it was not altered in
any other segment of the nephron. These results demonstrate that kidney
NEM-sensitive ATPase is under the control of corticosteroids and suggest
that mineralocorticoids rather than glucocorticoids are involved in this
regulation that specifically occurs in mineralocorticoid-sensitive nephron
segments. This paper also describes a new computerized method for the
automatic determination of the length of single nephron segments.
