Prostaglandin E2 enhances acetylcholine-induced, Ca2+-dependent ionic currents in swine tracheal mucous gland cells.
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.
Liu
Huiling
H
Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, Mississippi 39216-4624, USA.
Farley
Jerry M
JM
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
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