AJP - Renal Physiology, Vol 253, Issue 5 868-F873, Copyright © 1987 by American Physiological Society
Effects of indomethacin on renal response to atrial natriuretic peptide
C. A. Gaillard, H. A. Koomans, A. J. Rabelink and E. J. Mees
Department of Nephrology and Hypertension, University Hospital Utrecht, The Netherlands.
We studied the effect of alpha-human natriuretic peptide (ANP, 100
micrograms iv) on renal sodium handling in eight healthy subjects before
and after 7 days of indomethacin (50 mg 3 times a day). Sodium intake was
100 mmol/day. Prior to indomethacin, ANP caused a fourfold rise in sodium
excretion over the first 20 min and a threefold rise in fractional sodium
excretion. The clearance studies, performed during maximal water diuresis,
showed increased fractional free water clearance and lithium clearance.
Indomethacin caused marked sodium retention. Complete escape did not occur
until the sixth day, when cumulative balance was 244 mmol (range 176-337).
By this time renin and aldosterone were suppressed and fractional lithium
and free water clearance reduced. The natriuretic effect of ANP was not
attenuated, and the fractional excretion of sodium and chloride rose even
more than without indomethacin. The reduction in lithium and free water
clearance under indomethacin tended to be reversed by ANP. These data
suggest that the natriuretic effect of ANP is not mediated by or dependent
on renal prostaglandins. Indomethacin and ANP appear to have opposite
effects on sodium excretion, maximal free water clearance, and lithium
clearance.
