Renal and systemic hemodynamic effects of synthetic atrial natriuretic peptide in the anesthetized rat.

Abstract

To characterize the hemodynamic events responsible for alterations in renal function during administration of atrial natriuretic peptide, we studied the systemic, renal, and glomerular circulatory effects of intravenous rANP[126-149], administered as a 4 micrograms/kg prime and 0.5 microgram/kg per minute continuous infusion in anesthetized, euvolemic rats. With this protocol, a small decline in mean systemic arterial blood pressure occurred in the context of markedly enhanced urinary sodium excretion, hemoconcentration, and reduced left ventricular end-diastolic pressure and +dP/dt. However, despite a significant decrement in renal vascular resistance, total peripheral resistance remained constant, thereby denoting a preferential renal vasodilatory effect of this peptide in vivo. Whole kidney and single nephron GFR increased by approximately 20%, while effective renal and glomerular plasma flow rates remained stable, resulting in a substantial rise in filtration fraction. Of all the parameters potentially capable of augmenting single nephron GFR, only glomerular capillary hydraulic pressure increased significantly and therefore accounted entirely for the hyperfiltration observed during ANP infusion. This rise in glomerular capillary pressure, in turn, resulted from afferent arteriolar vasodilatation and concurrent efferent arteriolar vasoconstriction, findings that proved independent of both endogenous angiotensin II activity and ANP-induced reductions in renal perfusion pressure. These renal hemodynamic effects are unique when compared with actions of previously studied renal vasodilatory agents.

Atrial Natriuretic Peptide and Renal Haemodynamics in Newborn Calves

“…Using a similar experimental design, Eiskjaer et al (1996) and Janssen et al (1994) in adult humans, as well as Semmekrot et al (1990) in rabbits, observed these indices to decrease. On the other hand, no changes in renal blood (plasma) flow were found by Brown and Corr (1987) in humans, and by Dunn et al (1986) and Garcia-Estan and Roman (1990) in adult rats.…”

“…Conversely, Janssen et al (1994) in adult humans, Robillard et al (1988) in adult sheep, Seino et al (1988) in adult rabbits, andChevalier et al (1988) in adult rats, observed an increased glomerular filtration rate after administration of exogenous ANP. According to Dunn et al (1986) and Marin-Grez et al (1986), enhanced GFR may be a result of haemodynamics changes in the blood vessels of the glomeruli which lead to elevated glomerular filtration pressure. Conversely, Semmekrot et al (1990) observed decreasing GFR in young (4 -11 days old) and adult rabbits.…”

“…It has been recognised that ANP, through influence on glomerular afferent and efferent arterioles, may also affect renal blood (and plasma) flow and glomerular filtration rate (Dunn et al 1986;MarinGrez et al 1986). However, the literature provides discrepant information on the influence of ANP on renal haemodynamics (Abu-Amarah and Balment 1999; Eiskjaer et al 1996;Garcia-Estan and Roman 1990;Janssen et al 1994;Semmekrot et al 1990).…”

Beneficial Renal and Hemodynamic Effects of Omapatrilat in Mild and Severe Heart Failure

“…16,35 ANP increases efferent glomerular arteriolar tone, one mechanism by which GFR may be maintained in the current setting. 36,37 Our study did not allow direct comparison of omapatrilat with pure ACE inhibition. Nevertheless, there is clear evidence of dual neutral endopeptidase and ACE inhibition.…”

B‐type natriuretic peptide measurement in heart failure

“…34,35 Both ANP and BNP also improve renal blood flow via afferent arteriolar vasodilation and efferent arteriolar vasoconstriction. 36,37 There is also a direct effect on the collecting duct, leading to increased sodium excretion. 38 C-type natriuretic peptide acts primarily through a different receptor and plays a little known role in CHF.…”