Using a single blood sample and inulin to estimate glomerular filtration rate in rabbits

To establish a simple procedure for estimating the glomerular filtration rate (GFR) in conscious rabbits, we used the conventional multisample approach to develop a single-blood-sample method. A bolus injection of inulin was administered intravenously at a dose of 40 mg/kg to male New Zealand White rabbits, and blood was collected 30, 60, 90, and 120 min later. Serum inulin, urea nitrogen, and creatinine concentrations were determined. Using this multi-sample method, the reference GFR in clinically healthy rabbits was 4.01 ± 0.17 mL/min/kg (n = 17). In rabbits given an intravenous injection of the antitumor agent cisplatin, GFR fell before serum urea nitrogen and creatinine concentrations increased. Based on cumulative GFR data from healthy and nephropathy rabbits, the GFR obtained from the 3-sample method (30-, 60-, and 90-min samples) was closely correlated (r = 0.99) with that calculated from the estimated distribution volume and serum inulin concentration at 90 min after inulin injection in the single-blood-sample method. These results demonstrate that the single-blood-sample method supports sequential GFR measurements in rabbits and is a versatile procedure not only for research purposes but also in clinical settings.