Regulation of transepithelial phosphate transport by PTH in chicken proximal tubule epithelium.
The effect of parathyroid hormone (PTH) and activation of protein kinase C (PKC) and protein kinase A (PKA) on transepithelial P(i) transport was examined in monolayers of chick proximal tubule cells in primary culture (PTCs). Acute exposure of the PTCs to PTH (10(-9) M, basolateral side) significantly decreased the net reabsorption of P(i) by approximately 66%. There was no effect after the addition of PTH to the luminal side. Activation of PKC by phorbol 12-myristate 13-acetate (PMA; 0.1 microM) dramatically decreased net P(i) reabsorption by approximately 60%. Bisindolylmaleimide I (BIM; 1 microM), a highly selective PKC inhibitor, prevented PMA-induced inhibition. Activation of adenylate cyclase/PKA by forskolin (10 microM) mimicked the effect of PTH by significantly reducing net P(i) reabsorption by one-half. Addition of H-89 (10 microM), a potent inhibitor of PKA, abolished forskolin-induced inhibition. PTH inhibition was blocked by either BIM or H-89. Tissue electrophysiology remained stable after all treatments. There was a decreased immunoreactivity of the luminal Na+-P(i) cotransporter NaPi-IIa after PTH treatment. These data indicate that PTH inhibition of P(i) reabsorption in this in vitro system is mediated by PKC and PKA.
Dudas
Paul L
PL
Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269-4156, USA.
Villalobos
Alice R
AR
Gocek-Sutterlin
Gayle
G
Laverty
Gary
G
Renfro
J Larry
JL
D000818:Animals; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002273:Carcinogens / Q000494:pharmacology; D002478:Cells, Cultured; D002645:Chickens; D005576:Colforsin / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D007211:Indoles / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D007687:Kidney Tubules, Proximal / Q000166:cytology* / Q000378:metabolism*; D008301:Maleimides / Q000494:pharmacology; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010710:Phosphates / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D050608:Sodium-Phosphate Cotransporter Proteins; D013449:Sulfonamides; D027981:Symporters / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D002273:Carcinogens; D004791:Enzyme Inhibitors; D007211:Indoles; D007546:Isoquinolines; D008301:Maleimides; D010281:Parathyroid Hormone; D010710:Phosphates; D050608:Sodium-Phosphate Cotransporter Proteins; D013449:Sulfonamides; D027981:Symporters; D005576:Colforsin; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; C088060:bisindolylmaleimide; D013755:Tetradecanoylphorbol Acetate