AJP - Renal Physiology, Vol 251, Issue 5 795-F801, Copyright © 1986 by American Physiological Society
Effect of atrial natriuretic factor on renal hemodynamics in the rat
D. M. Pollock and W. J. Arendshorst
Clearance experiments were conducted to determine the effects of atrial
natriuretic factor (ANF) on renal hemodynamics and excretory function in
anesthetized, euvolemic Munich-Wistar rats. Intra-aortic infusions of
synthetic ANF (28 amino acids) at 7.5 and 15 micrograms X kg-1 X h-1
produced dose-related increases in absolute and fractional sodium and water
excretion under steady-state conditions; renal blood flow (RBF) was
unchanged, whereas mean arterial pressure significantly decreased but
remained within the autoregulatory range. An apparent maximal response was
elicited by 15 micrograms X kg-1 X h-1 as 30 micrograms X kg-1 X h-1
produced a similar increase in urine flow and sodium excretion. ANF
infusion at 30 micrograms X kg-1 X h-1 produced no transient or sustained
changes in RBF (electromagnetic flow probe). Renal vascular resistance was
significantly decreased in parallel with reductions in arterial pressure;
ANF-induced changes in resistance can be explained by autoregulatory
adjustments. In another series, intra-aortic vs. intravenous infusion of
ANF (7.5 micrograms X kg-1 X h-1) were compared in the same animal; the
diuretic and natriuretic response to ANF was similar with the two routes of
administration. We observed no consistent changes in glomerular filtration
rate (GFR). Our results indicate that the diuretic and natriuretic effects
of synthetic ANF in the rat do not require an increase in RBF or GFR.
