Experiments with the double isotope single-injection method for determining glomerular filtration rate and effective...

Single injections of the radiochemicals Cr51-EDTA and I125-ortho-iodohippurate (I125-OH) were used simultaneously to measure the glomerular filtration rate (GFR) and effective renal plasma flow (ERPF), respectively, in 26 calves weighing between 37 kg and 90 kg. The mean GFR was 2.31 ml per minute per kg and the mean ERPF was 9.62 ml per minute per kg. These values are very similar to the GFR and ERPF measured in young calves and adult cattle by using constant infusions of inulin and para-aminohippurate as marker substances. Correlation coefficients of the order of 0.70 were found between clearance values and body-weights. The method described is rapid and reliable.