Comparative study of glomerular filtration rate with diverse labelled agents.

Clearances of 113mIn-EDTA, or 99mTc -DTPA or 131I-iothalamate were compared with 3H-inulin simultaneously in rabbits or dogs. The classical plateau method was explored followed by a second slope in some instances or by the single shot procedure in others. A two-compartmental mathematical model was always employed to compare and calculate. The study suggests that the diverse agents tested are handled following similar homeostatic trends and values, although the intervening membranes may act upon them individually with diffusion rates that may vary in relation to each substance, in particular at a given time interval.