title: Regulation of sodium absorption by canine tracheal epithelium.
abstract: To regulate the quantity of respiratory tract fluid, the airway epithelium either secretes chloride, Cl-, or reabsorbs sodium, Na+. Many secretagogues inhibit Na+ absorption, but the decrease may result from a fall in the electrochemical gradient for Na+ absorption. We examined regulation of Na+ absorption independent of Cl- secretion, by bathing canine tracheal epithelium in Cl--free, gluconate Ringers solution. Prostaglandin E2, 2-chloroadenosine, and isoproterenol increased short-circuit current (Isc) and the rate of Na+ absorption. In contrast, indomethacin, which inhibits endogenous prostaglandin production, decreased Isc. These agents regulate cellular levels of cAMP; direct addition of 8-Br-cAMP also acutely increased Isc. We examined chronic regulation of Na+ absorption in cell monolayers grown on permeable supports in serum-free media. Exposure to aldosterone for two days increased baseline Isc by 50% and the amiloride-inhibitable current by 55%. These data indicate that Na+ absorption is both acutely and chronically regulated in the airway epithelium.
mesh_terms: D015762:2-Chloroadenosine; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D000450:Aldosterone / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002417:Cattle; D004553:Electric Conductivity; D004848:Epithelium / Q000378:metabolism; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D011458:Prostaglandins E / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*; D014132:Trachea / Q000378:metabolism*; D014882:Water-Electrolyte Balance / Q000187:drug effects
chemical_list: D011458:Prostaglandins E; D015762:2-Chloroadenosine; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000001:Calcimycin; D000450:Aldosterone; D000584:Amiloride; D012964:Sodium; D000241:Adenosine; D007545:Isoproterenol; D007213:Indomethacin