Renal function in domestic fowl

Abstract

Roosters were exposed to water and salt loading and to dehydration. The ureteral urine was collected through polyethylene funnels. The glomerular filtration rate (GRF) was found to increase an average of 23% from dehydration to hydration, when at the same time the urine flow increased from 20 [mu]l/min per kg to 300 [mu]l/min per kg (1,500%). At the same time the osmolal urine-to-plasma ratio varied from 1.58 to 0.37 and the excretion of water changed from 1 to 14% of the filtered load. From dehydration to hydration the salt output increased from approximately 1 to 2.5% of the filtered load. Salt loading (12-15 mEq/kg body wt) did not reduce the GRF. In ducks and turkeys a similar concentrating capacity was found. The renal function of the bird resembles that of mammals with respect to the very stable filtration rate and the capacity to dilute and concentrate the urine. It resembles that of reptiles and other lower vertebrates with respect to the small fraction of filtrate that is resorbed during hydration and with respect to the effect of dehydration on tubular sodium resorption.