AJP - Regulatory, Integrative and Comparative Physiology, Vol 268, Issue 3 577-R582, Copyright © 1995 by American Physiological Society
Effect of somatolactin and related hormones on phosphate transport by flounder renal tubule primary cultures
M. Lu, P. Swanson and J. L. Renfro
Department of Physiology and Neurobiology, University of Connecticut, Storrs 06269.
Winter flounder renal proximal tubule primary monolayer cultures mounted in
Ussing chambers were used to determine the effect of salmon somatolactin
(sSL) on transepithelial Pi and Ca2+ transport. sSL stimulated Pi
reabsorption in a dose-dependent manner at physiological levels of the
hormone (12.5 ng/ml). Net Pi transport was significantly altered by sSL
(200 ng/ml) within 2 h after the initial exposure. Ca2+ fluxes were
unchanged by the addition of 200 ng/ml sSL. The sSL-induced Pi reabsorption
was abolished by 10 microM H-89, a highly specific protein kinase A
inhibitor. Moreover the production and release of adenosine 3',5'-cyclic
monophosphate were significantly increased after 1 and 2 h of exposure to
sSL. The data indicate that sSL directly stimulates net renal Pi
reabsorption by an adenosine 3',5'-cyclic monophosphate-dependent pathway.
In addition to sSL, flounder SL and rat prolactin greatly, and salmon
growth hormone (2.3 micrograms/ml) slightly, increased net Pi reabsorptive
flux, whereas salmon prolactin had no effect.
