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 filtrat ion rate (GFR) and effective renal plasma flow (ERPF) in chickens was compared with the continuous-infusion method. Male and female White Le ghorn chickens were anesthetized, and catheters were placed in both br achial veins and over both ureteral openings. A single-bolus injection of H-3-inulin and C-14-para-aminohippuric acid was given at a dose of 1.0 mu Ci 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 mu Ci of H-3-inulin/kg and 1 mu Ci of C-14-para-aminohippuric acid/kg, followed by a constant infusion of 0.1 mu Ci of each solute/min at a rate of 0.1 ml.kg(-1).h(-1) Followi ng a 45-min stabilization period, three continuous urine collections w ere performed. A blood sample was obtained at the midpoint of each uri ne collection. The GFR and ERPF determined by the single-injection met hod (3.12 +/- 0.43 and 22.81 +/- 3.48 ml.min(-1) kg(-1), respectively) were comparable to values for the continuous-infusion method (2.81 +/ - 0.35 and 22.88 +/- 4.03 ml.min(-1).kg(-1), respectively). Both GFR a nd ERPF determined by the single-injection method correlated with GFR and ERPF determined by the continuous-infusion method. This single-inj ection method provides a rapid, accurate method for determining GFR an d ERPF in chickens and eliminates the need for collection of urine.