AJP - Renal Physiology, Vol 238, Issue 5 380-F386, Copyright © 1980 by American Physiological Society
Renal potassium adaptation: Na-K-ATPase activity along the nephron after chronic potassium loading
A. Doucet and A. I. Katz
To identify nephron sites where renal potassium adaptation takes place,
Na-K-ATPase was measured with a micromethod along the nephron of
potassium-loaded mice. A possible role of aldosterone in this process was
evaluated in K-loaded animals treated concurrently with pharmacologic doses
of spironolactone. Animals fed a potassium-enriched diet for at least 2 wk
excreted about 90% of ingested potassium in the urine, and fractional
potassium clearance averaged 87 +/- 8%, compared with 13 +/- 2% in
controls. Na-K-ATPase activity per millimeter tubule length increased by
225% in the cortical collecting tubule and by 177% in the medullary
collecting tubule, but was not substantially affected in other nephron
segments. Stimulation of Na-K-ATPase was identical in the cortical
collecting tubule of K-loaded mice treated with spironolactone. These
results indicate that chronic potassium loading in the mouse results in an
adaptive increase potassium loading in the mouse results in an adaptive
increase in Na-K-ATPase in the collecting tubule and suggest that this
nephron segment is the major site of potassium adaptation in this species.
This effect appears to be independent of aldosterone.
