Stanniocalcin stimulates phosphate reabsorption by flounder renal proximal tubule in primary culture.

Abstract

The effects of several hormones on transepithelial Pi transport were determined in primary monolayer cultures of winter flounder proximal tubule epithelium in Ussing chambers. Salmon stanniocalcin (STC) had a dose-dependent stimulatory effect on net Pi reabsorption within the normal plasma hormone concentration range, 12.5-50 ng/ml (0.25-1.0 nM). Net Pi transport was significantly altered by STC (200 ng/ml) within 30 min and progressively increased from slight net secretion (0.26 +/- 0.744 nmol.cm-2.h-1) in untreated controls to net reabsorption (1.96 +/- 0.729 nmol.cm-2.h-1) after 3 h. The STC effect was mimicked by 10 microM forskolin, whereas 10 microM H-89, a highly specific protein kinase A inhibitor, significantly decreased both STC- and forskolin-induced Pi reabsorption. The release of adenosine 3',5'-cyclic monophosphate (cAMP) was increased more than twofold after a 1-h exposure to STC. This hormone had no effect on transepithelial Ca2+ transport. The results indicate that STC directly stimulates net renal Pi reabsorption by a cAMP-dependent pathway. In addition to STC, bovine parathyroid hormone (100 nM) and ovine prolactin (100 nM) significantly increased net Pi reabsorptive flux.