title: Prostanoids secreted by alveolar macrophages enhance ionic currents in swine tracheal submucosal gland cells.
abstract: We examined the effect of substances released by swine alveolar macrophages (AMs) on ionic currents in airway submucosal gland cells (SGCs). AMs obtained by lavage were activated by 24-h zymosan exposure (0.1 mg/ml). Supernatant was collected and used to stimulate short-circuit current changes (DeltaI(SC)) in SGC monolayers in Ussing chambers. Dexamethasone (1 microM) or indomethacin (5 muM) during zymosan exposure of AMs reduced or abolished the supernatant-induced DeltaI(SC). Zymosan exposure induced a 5-fold increase in cyclooxygenase (COX)-2 but not COX-1 protein levels in AMs. Prostaglandin E(2) (PGE(2)) concentration in the supernatant from zymosan-activated AMs was 550 +/- 10 nM (n = 3) compared with 28 +/- 3 nM for unstimulated AMs (n = 3). PGE(2), applied serosally, induced DeltaI(SC) with an EC(50) of 15.5 +/- 1.3 nM (n = 4) and 3.6 +/- 1.8 microM (n = 3) when applied apically. Four types of endoprostanoid receptors (EP(1-4)) were detected in SGCs using Western blot. PGE(2)-induced DeltaI(SC) were inhibited by AH6809 (6-isopropoxy-9-oxoxanthene-2-carboxylic acid) but not by SC19220 (8-chloro-dibenzo[b,f][1,4]oxazepine-10(11H)-carboxylic acid, 2-acetylhydrazide), suggesting that endoprostanoid (EP)(2) but not EP(1) receptors were activated by PGE(2). Pretreatment of SGCs with supernatant from zymosan-activated AMs, PGE(2), or forskolin enhanced the sensitivity to acetylcholine (ACh)-induced DeltaI(SC). PGE(2)-induced DeltaI(SC) were blocked by charybdotoxin (ChTX), chromanol 293B, or glibenclamide. ACh-induced DeltaI(SC) were only blocked by ChTX or glibenclamide. None of these blockers altered PGE(2) pretreatment-induced sensitization of ACh-induced DeltaI(SC). These results demonstrate that prostanoids released from activated AMs directly increase cystic fibrosis transmembrane conductance regulator and K(+) channel activity. ACh-induced DeltaI(SC) are also enhanced due to enhanced activation of Ca(2+)-activated K(+) channels (K(Ca)).
authors.affiliation: Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, 39216, USA.
authors.forename: Huiling
authors.initials: H
authors.lastname: Liu
authors.forename: Abulkhair M
authors.initials: AM
authors.lastname: Mamoon
authors.forename: Jerry M
authors.initials: JM
authors.lastname: Farley
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D051546:Cyclooxygenase 2 / Q000096:biosynthesis; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D015194:Diffusion Chambers, Culture; D015232:Dinoprostone / Q000378:metabolism / Q000494:pharmacology; D005088:Exocrine Glands / Q000378:metabolism*; D007213:Indomethacin / Q000494:pharmacology; D007473:Ion Channels / Q000378:metabolism*; D016676:Macrophages, Alveolar / Q000378:metabolism*; D008297:Male; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D011453:Prostaglandins / Q000378:metabolism* / Q000502:physiology*; D013552:Swine; D014132:Trachea / Q000378:metabolism*; D015054:Zymosan / Q000494:pharmacology
chemical_list: D018118:Chloride Channels; D016861:Cyclooxygenase Inhibitors; D007473:Ion Channels; D015221:Potassium Channels; D011453:Prostaglandins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D005576:Colforsin; D003907:Dexamethasone; D015054:Zymosan; D051546:Cyclooxygenase 2; D015232:Dinoprostone; D000109:Acetylcholine; D007213:Indomethacin