Modulation of kidney function in conscious Pekin ducks by atrial natriuretic factor

The influence of avian atrial natriuretic factor (ANF) on renal function was examined in conscious saltwater-acclimated Pekin ducks undergoing a steady state diuresis maintained by iv infused isotonic avian Krebs-Ringer solution at a rate of 1.0 ml/min. Synthetic chicken ANF (chANF) was applied iv at doses of 10, 50, and 90 ng/min.kg BW for 10 min and caused dose-dependent transient increases in urine flow, osmolal excretion, glomerular filtration rate, effective renal plasma flow, and fractional water clearance at decreased urinary osmolality. Using receptor autoradiography, binding sites for [125I]Bolton-Hunter-labeled chANF [( 125I]BH-chANF) were localized in both the reptilian-type glomeruli and the collecting duct system throughout the duck kidney. A RRA for [125I]BH-chANF, established using an enriched kidney membrane fraction, indicated that unlabeled chANF and human ANF competitively displaced [125I]BH-chANF with comparable potencies. ANF-induced modulation of renal salt and water elimination via glomerular and tubular receptor interactions is consistent with the concept that this hormone has a physiological role in avian volume homeostasis.