title: Prostaglandin E2 enhances acetylcholine-induced, Ca2+-dependent ionic currents in swine tracheal mucous gland cells.
abstract: Airway submucosal gland cell (SMGC) secretions are under the control of various neurotransmitters and hormones. Interactions between different pathways, such as those mediated by cAMP and Ca(2+), in controlling mucus or electrolyte secretions are not well understood. Prostaglandin E(2) (PGE(2)) or forskolin has been shown to enhance acetylcholine (ACh)-induced short circuit current (I(SC)) in SMGC mucous cell monolayers. We show that PGE(2), by activating cAMP-dependent protein kinase A (PKA), enhanced ACh-induced, Ca(2+)-mediated current and changes in [Ca(2+)](i) in mucous cells. PGE(2) pretreatment sensitized ACh-induced I(SC) (DeltaI(SC)) by activating endoprostanoid (EP(2)) receptors. PKA inhibitors 14-22 amide PKI (PKI) and Rp-diastereomer (Rp) of cAMPs prevented the effect of PGE(2). Removing external Ca(2+) or pretreatment with the Ca(2+) entry blocker, SKF96365 [1-[beta-(3-(4-methoxyphenyl) propoxy)-4-methoxyphenethyl]-1H-imidazole hydrochloride1-[2-(4-methoxyphenyl)-2-[3-(4-methoxyphenyl) propoxy] ethyl] imidazole], shifted the concentration-response relationships for ACh to the right but did not abolish PGE(2)-induced sensitization of the ACh response. An inositol 1,4,5-trisphosphate (IP(3)) receptor antagonist and Ca(2+) entry blocker, 2-aminoethoxydiphenyl borate, abolished the ACh-induced response. Charybdotoxin, but not iberiotoxin (IbTX), inhibited the ACh-induced DeltaI(SC). Clotrimazole, but not IbTX, inhibited the ACh-induced serosal K(+) current. Under whole-cell patch clamp, ACh-induced K(+) and Cl(-) currents were coincident with increases in [Ca(2+)](i) in single mucous cells. PGE(2) or forskolin pretreatment did not induce current or [Ca(2+)](i) changes but enhanced ACh-induced currents, membrane hyperpolarization, and [Ca(2+)](i) changes. Intra-cellular dialysis with the PKA-catalytic subunit enhanced ACh-induced whole-cell current as well. These findings demonstrate that PGE(2), via EP(2) receptors and the cAMP/PKA pathway, activates Ca(2+) entry-independent mechanisms, possibly by increasing IP(3)-mediated Ca(2+) release, resulting in the sensitization of ACh-induced currents.
authors.affiliation: Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, Mississippi 39216-4624, USA.
authors.forename: Huiling
authors.initials: H
authors.lastname: Liu
authors.forename: Jerry M
authors.initials: JM
authors.lastname: Farley
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001896:Boron Compounds / Q000494:pharmacology; D002118:Calcium / Q000172:deficiency / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002352:Carrier Proteins / Q000494:pharmacology; D002478:Cells, Cultured; D018999:Charybdotoxin / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology*; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D007093:Imidazoles / Q000494:pharmacology; D007473:Ion Channels / Q000502:physiology*; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000037:antagonists & inhibitors / Q000502:physiology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009092:Mucous Membrane / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D010446:Peptide Fragments / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D011448:Prostaglandin Antagonists / Q000494:pharmacology; D013552:Swine; D014132:Trachea / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D044004:Xanthones / Q000494:pharmacology
chemical_list: D001896:Boron Compounds; D002121:Calcium Channel Blockers; D002352:Carrier Proteins; D007093:Imidazoles; D007473:Ion Channels; D051036:Large-Conductance Calcium-Activated Potassium Channels; D010446:Peptide Fragments; D010455:Peptides; D026902:Potassium Channel Blockers; D011448:Prostaglandin Antagonists; D044004:Xanthones; C477818:myristoylated protein kinase A inhibitor amide 14-22; D018999:Charybdotoxin; D005576:Colforsin; C053876:6-isopropoxy-9-oxoxanthene-2-carboxylic acid; C064719:iberiotoxin; C109986:2-aminoethoxydiphenyl borate; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole; D015232:Dinoprostone; D000109:Acetylcholine; D002118:Calcium