Use of a single injection solute-clearance method for determination of glomerular filtration rate and effective renal plasma flow in chickens.

A single-injection clearance method for determining glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) in chickens was compared with the continuous-infusion method. Male and female White Leghorn chickens were anesthetized, and catheters were placed in both brachial veins and over both ureteral openings. A single-bolus injection of 3H-inulin and 14C-para-aminohippuric acid was given at a dose of 1.0 microCi of each solute per kg of body weight and nine blood samples were obtained over 60 min. After the last sample was taken, the birds were given a bolus injection of 1 microCi of 3H-inulin/kg and 1 microCi of 14C-para-aminohippuric acid/kg, followed by a constant infusion of 0.1 microCi of each solute/min at a rate of 0.1 ml.kg-1 x h-1. Following a 45-min stabilization period, three continuous urine collections were performed. A blood sample was obtained at the midpoint of each urine collection. The GFR and ERPF determined by the single-injection method (3.12 +/- 0.43 and 22.81 +/- 3.48 ml.min-1 x kg-1, respectively) were comparable to values for the continuous-infusion method (2.81 +/- 0.35 and 22.88 +/- 4.03 ml.min-1 x kg-1, respectively). Both GFR and ERPF determined by the single-injection method correlated with GFR and ERPF determined by the continuous-infusion method. This single injection method provides a rapid, accurate method for determining GFR and ERPF in chickens and eliminates the need for collection of urine.