UTP-dependent inhibition of Na+ absorption requires activation of PKC in endometrial epithelial cells.
The objective of this study was to investigate the mechanism of uridine 5'-triphosphate (UTP)-dependent inhibition of Na(+) absorption in porcine endometrial epithelial cells. Acute stimulation with UTP (5 microM) produced inhibition of sodium absorption and stimulation of chloride secretion. Experiments using basolateral membrane-permeabilized cell monolayers demonstrated a reduction in benzamil-sensitive Na(+) conductance in the apical membrane after UTP stimulation. The UTP-dependent inhibition of sodium transport could be mimicked by PMA (1 microM). Several PKC inhibitors, including GF109203X and Gö6983 (both nonselective PKC inhibitors) and rottlerin (a PKCdelta selective inhibitor), were shown to prevent the UTP-dependent decrease in benzamil-sensitive current. The PKCalpha-selective inhibitors, Gö6976 and PKC inhibitor 20-28, produced a partial inhibition of the UTP effect on benzamil-sensitive Isc. Inhibition of the benzamil-sensitive Isc by UTP was observed in the presence of BAPTA-AM (50 microM), confirming that activation of PKCs, and not increases in [Ca(2+)](i), were directly responsible for the inhibition of apical Na(+) channels and transepithelial Na(+) absorption.
Palmer-Densmore
Melissa
M
Department of Physiology, University of Minnesota, St Paul, MN 55108, USA.
Deachapunya
Chatsri
C
Kannan
Mathur
M
O'Grady
Scott M
SM
D000042:Absorption / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002352:Carrier Proteins / Q000494:pharmacology; D004717:Endometrium / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D005260:Female; D047908:Intracellular Signaling Peptides and Proteins; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D013552:Swine; D014544:Uridine Triphosphate / Q000502:physiology*
D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; C015482:protein kinase modulator; D012964:Sodium; D011493:Protein Kinase C; D014544:Uridine Triphosphate