Noradrenergic modulation of avian kidney function

Norepinephrine (NE) infused at doses of 0.7, 2.2 and 6.7 micrograms/min/kg body weight into conscious, salt and water loaded ducks dose-dependently induced arterial hypertension, reflex bradycardia and diuresis/natriuresis at unchanged glomerular filtration and reduced renal blood flow. NE-induced changes in plasma concentrations of osmoregulatory hormones consisted of a slight increase for the antidiuretic hormone, no change for angiotensin II and a nearly 4-fold increase for atrial natriuretic factor. Sub-pressor doses of NE infused close to the origin of the renal arteries induced diuresis without a rise in urinary sodium concentration. The results suggest pressure diuresis in ducks as a response to hypertensive NE doses with a possible contribution of atrial natriuretic factor to natriuresis.