title: Mechanisms of electrolyte transport across the endometrium. I. Regulation by PGF2 alpha and cAMP.
abstract: The purpose of this study was to characterize the transport mechanisms in endometrial epithelial cells that are responsible for regulation of Na and K concentrations in uterine luminal fluid. Porcine endometrial tissues were mounted in Ussing chambers and bathed in plasmalike Ringer solution. The mean basal short-circuit current (Isc) was 40 microA/cm2, and the mean tissue conductance was 3.6 mS/cm2. Addition of amiloride to the luminal solution inhibited 86% of the basal Isc. Concentration-response experiments using amiloride analogues showed a rank order of potency of benzamil > amiloride > 5-(N-methyl-N-isobutyl)-amiloride in blocking the Isc, with no response to ethylisopropylamiloride. Na channel immunoreactivity was localized to the apical membrane of surface epithelial cells. The Na-to-K selectivity ratio of the amiloride-sensitive Na channel was calculated to be 6.4:1. Prostaglandin (PG) F2 alpha or 8-(chlorophenylthio)-adenosine 3',5'-cyclic monophosphate (CPT-cAMP) added to the luminal solution stimulated a twofold increase in Isc that was inhibited by pretreatment with amiloride. Experiments using both amphotericin B-permeabilized tissues and intact tissues showed that PGF2 alpha and cAMP increased Na absorption by activation of basolateral K channels. Treatment of the luminal solution with 4-aminopyridine produced an effect on Isc that was consistent with block of K secretion and a subsequent decrease in Na absorption. These experiments showed that Na and K transport are tightly coupled processes occurring under basal conditions in surface endometrial epithelial cells and that these processes are regulated by PGF2 alpha and cAMP.
authors.affiliation: Department of Veterinary PathoBiology, University of Minnesota, St. Paul 55108, USA.
authors.forename: A E
authors.initials: AE
authors.lastname: Vetter
authors.forename: S M
authors.initials: SM
authors.lastname: O'Grady
mesh_terms: D015761:4-Aminopyridine / Q000494:pharmacology; D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000494:pharmacology; D001692:Biological Transport; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology / Q000502:physiology*; D015237:Dinoprost / Q000494:pharmacology / Q000502:physiology*; D004553:Electric Conductivity; D004573:Electrolytes / Q000378:metabolism*; D004717:Endometrium / Q000378:metabolism* / Q000502:physiology; D005260:Female; D007150:Immunohistochemistry; D010539:Permeability; D011188:Potassium / Q000378:metabolism; D015222:Sodium Channels / Q000378:metabolism; D013552:Swine; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D004573:Electrolytes; D015222:Sodium Channels; D013873:Thionucleotides; D001464:Barium; C015929:8-((4-chlorophenyl)thio)cyclic-3',5'-AMP; D000584:Amiloride; D015237:Dinoprost; D015761:4-Aminopyridine; D000242:Cyclic AMP; D011188:Potassium