Single nephron glomerular filtration rate ratios of superficial, intercortical and juxtamedullary nephrons in rats during development.

In 20, 40 and 60-day-old rats the filtration rate was studied using Baines modification of Hanssen's Na4Fe (14CN)6 method enabeling the determination of single nephron glomerular filtration rate (SNGFR) ratio between superficial (S), intercortical (I) and juxtamedullary (J) nephrons. The proximal tubule lengths were determined as well. A close correlation was obtained between age and S/I, I/J and S/J of proximal tubule lengths and between age and I/J, S/J 14C-activities of ferro-cyanide. Presented findings confirm the data on the increasing role of superficial nephrons in the course of postnatal development of rat.