AJP - Renal Physiology, Vol 249, Issue 2 315-F318, Copyright © 1985 by American Physiological Society
Synthetic atrial natriuretic factor decreases renal tubular phosphate reabsorption in rats
T. G. Hammond, A. Haramati and F. G. Knox
Atrial natriuretic factor (ANF), a family of peptides isolated from cardiac
atria, has marked effects on sodium excretion. A synthetic 26 amino acid
sequence of ANF peptide has also been shown to be phosphaturic. However, it
is difficult to assess whether the phosphaturia is due to changes in
tubular reabsorption of phosphate without control of filtered load of
phosphate. In the present study, the hypothesis that ANF peptide decreases
tubular phosphate reabsorption was tested by using graded phosphate
infusions of 0, 1, 2, and 3 mumol/min in thyroparathyroidectomized rats.
Further, reabsorbed phosphate was similarly assessed in rats infused with
parathyroid hormone (PTH) to allow comparison with a known phosphaturic
hormone. ANF peptide decreased reabsorbed phosphate compared with saline
controls (2.72 +/- 0.28 mumol/ml GFR compared with 3.35 +/- 0.35, P less
than 0.05) but not as much as a maximally phosphaturic dose of PTH (2.04
+/- 0.13 mumol/ml GFR). We conclude that synthetic ANF peptide decreases
tubular phosphate reabsorption in vivo.
