Rat Atrial Natriuretic Factor (ANP-III) Inhibits Phosphate Transport in Brush Border Membrane from Superficial and Juxtamedullary Cortex 1

Abstract

Abstract

Previous studies have shown that administration of synthetic atrial natriuretic factor (ANF, 101–126) decreases sodium-dependent phosphate transport across renal brush border membrane vesicles (BBMV) in rats fed a normal or low phosphate diet. In the present study, infusion of rat ANF (atriopeptin III (ANP-III), 103–126 rat ANF) to rats fed a normal phosphate diet caused natriuretic and phosphaturic effects similar to those of ANF (101–126), but unlike ANF (101–126) did not increase the glomerular filtration rate. The effect of ANP-III infusion on sodium-dependent transport of phosphate was also determined in BBM vesicles isolated from the superficial cortex (BBMV-SC) and juxtamedullary cortex (BBMV-JM). The results indicate that ANP-III decreases phosphate transport across BBMV-SC and BBMV-JM similarly (20–24%). However, it had no effect on sodium-dependent transport of proline in these vesicles.

The infusion of ANP-III to rats fed a normal phosphate diet inhibits phosphate uptake both in BBMV-SC and BBMV-JM and causes phosphaturia without increments in glomerular filtration rate.