Determination of glomerular filtration rate in the rat using 51Cr-EDTA and a single blood sample

51Cr-labeled ethylenediaminetetraacetic acid (EDTA) was used to measure the glomerular filtration rate in rats using external body counting and a two-compartmental analysis according to the method of Sapirstein. A comparison was made of results calculated using the two-compartment method and a recently proposed formula requiring a knowledge of the distribution volume of the isotope and the analysis of a single timed plasma sample. The results have shown that the formula of Bryan et al. can be used for the rapid and convenient determination of glomerular filtration rate in small animals after the administration of 51Cr-EDTA.