Tubular localization of adaptation to dietary phosphate in rats
Mühlbauer, R.C.; Bonjour, J.P.; Fleisch, H.
American Journal of Physiology 233(4): F342-F348
1977
ISSN/ISBN: 0002-9513 PMID: 910958 Document Number: 118645
For 10 days male Wistar rats weighing 240 g were pair-fed on a diet containing P 0.2 or 1.8%. Free-flow micropunctures under acute infusion of inorganic phosphate (Pi) were made at increased but similar filtered loads of Pi to give 6.07 and 5.34 mu mol/kidney min for the respective diets. Fractional excretion of Pi for whole kidney was 0.26 and 0.67%. The fraction of filtered Pi at different puncture sites suggests that part of the adaptation to dietary Pi occurs in the early proximal tubule. An effect in the later part of the proximal convoluted tubule cannot be excluded. Pi in the diet affects the difference in Pi delivery between the distal tubule and final urine. This could be the result of a greater adaptive response of deep nephrons or could indicate that an adaptation with a secretory component takes place along the terminal part of the nephrons.