Cardiorenal Reflexes Do Not Attenuate the Renal Effects of Infused Atriopeptin in Conscious Dogs

Abstract

Abstract

Low-dose infusions of atriopeptin produce only a modest diuresis and natriuresis. However, these infusions also decrease atrial pressures, a change that has been postulated to elicit an antidiuretic and antinatriuretic reflex from cardiac receptors and thereby to attenuate the direct renal effects of atriopeptin. To determine whether the renal effects of intravenously administered atriopeptin might be attenuated by a cardiorenal reflex, we infused α-human atrial natriuretic peptide (α-hANP) into cardiac-denervated and sham-operated (normal) conscious dogs. Following a control period, α-hANP was infused into each dog at 12.5, 25, or 50 ng·kg⁻¹·min⁻¹ for 1 hr. Infusion of α-hANP at 50 ng·kg⁻¹·min⁻¹ produced similar decreases in left atrial pressure in both normal and cardiac-denervated dogs (peak changes, −1.6 ± 0.8 vs −2.4 ± 0.9 mm Hg, respectively). Increases in urine flow (peak changes, 0.13 ± 0.05 vs 0.20 ± 0.06 ml/min) and sodium excretion (peak changes, 56 ± 22 vs 70 ± 11 μEq/min) also were not different between groups. The lower doses of α-hANP also elicited renal and hemodynamic responses in the cardiac-denervated dogs that did not differ significantly from those in the normal dogs. These data indicate that the diuresis and natriuresis elicited by intravenously administered α-hANP are not attenuated by a cardiorenal reflex in conscious dogs.