NORADRENERGIC MODULATION OF AVIAN KIDNEY-FUNCTION

Norepinephrine (NE) infused at doses of 0.7, 2.2 and 6.7 mu g/min/kg b ody weight into conscious, salt and water loaded ducks dose-dependentl y induced arterial hypertension, reflex bradycardia and diuresis/natri uresis at unchanged glomerular filtration and reduced renal blood flow . NE-induced changes in plasma concentrations of osmoregulatory hormon es consisted of a slight increase for the antidiuretic hormone, no cha nge for angiotensin II and a nearly 4-fold increase for atrial natriur etic factor. Sub-pressor doses of NE infused close to the origin of th e renal arteries induced diuresis without a rise in urinary sodium con centration. The results suggest pressure diuresis in ducks as a respon se to hypertensive NE doses with a possible contribution of atrial nat riuretic factor to natriuresis.