AJP - Renal Physiology, Vol 253, Issue 3 424-F431, Copyright © 1987 by American Physiological Society
Renal autoregulation and pressure natriuresis during ANF-induced diuresis
R. V. Paul, K. A. Kirk and L. G. Navar
We examined the autoregulation of renal blood flow (RBF) and glomerular
filtration rate (GFR) in the anesthetized dog during selective renal
arterial infusion of two different synthetic atrial natriuretic factor
(ANF) analogues. Rat atriopeptin II (5 X 10(-8) M in renal arterial blood)
caused increases in sodium and water excretion but left RBF and GFR
unchanged. A similar response was seen with rat 8-33 atrial natriuretic
peptide (ANP) (10(-9) M), but a twofold higher dose of this peptide
produced a transient increase in RBF and a sustained 16% increase in GFR.
The normal pattern of RBF autoregulation in response to decreases in renal
perfusion pressure was not altered by either peptide. GFR was also
efficiently autoregulated during ANF infusion; however, there was a
threefold increase in the slope of the relationship between sodium
excretion and arterial pressure (pressure natriuresis) during 8-33 ANP
infusion (control 1.11 +/- 0.39, 8-33 ANP 4.00 +/- 0.86 mu eq/mmHg, P less
than 0.01). We conclude that ANF-induced diuresis can be sustained without
detectable changes in either the autoregulation-responsive or
autoregulation-independent components of renal vascular resistance. Factors
other than GFR, which are highly responsive to renal perfusion pressure,
are important in modulating the natriuresis caused by ANF. The augmentation
of pressure natriuresis within the GFR autoregulatory range suggests an
influence of ANF on the magnitude of arterial pressure-induced changes in
tubular sodium reabsorption.
