title: Capsaicinoids regulate airway anion transporters through Rho kinase- and cyclic AMP-dependent mechanisms.
abstract: To investigate the effects of capsaicinoids on airway anion transporters, we recorded and analyzed transepithelial currents in human airway epithelial Calu-3 cells. Application of capsaicin (100 μM) attenuated vectorial anion transport, estimated as short-circuit currents (I(SC)), before and after stimulation by forskolin (10 μM) with concomitant reduction of cytosolic cyclic AMP (cAMP) levels. The capsaicin-induced inhibition of I(SC) was also observed in the response to 8-bromo-cAMP (1 mM, a cell-permeable cAMP analog) and 3-isobutyl-1-methylxanthine (1 mM, an inhibitor of phosphodiesterases). The capsaicin-induced inhibition of I(SC) was attributed to suppression of bumetanide (an inhibitor of the basolateral Na(+)-K(+)-2 Cl(-) cotransporter 1)- and 4,4'-dinitrostilbene-2,2'-disulfonic acid (an inhibitor of basolateral HCO(3)(-)-dependent anion transporters)-sensitive components, which reflect anion uptake via basolateral cAMP-dependent anion transporters. In contrast, capsaicin potentiated apical Cl(-) conductance, which reflects conductivity through the cystic fibrosis transmembrane conductance regulator, a cAMP-regulated Cl(-) channel. All these paradoxical effects of capsaicin were mimicked by capsazepine. Forskolin application also increased phosphorylated myosin phosphatase target subunit 1, and the phosphorylation was prevented by capsaicin and capsazepine, suggesting that these capsaicinoids assume aspects of Rho kinase inhibitors. We also found that the increments in apical Cl(-) conductance were caused by conventional Rho kinase inhibitors, Y-27632 (20 μM) and HA-1077 (20 μM), with selective inhibition of basolateral Na(+)-K(+)-2 Cl(-) cotransporter 1. Collectively, capsaicinoids inhibit cAMP-mediated anion transport through down-regulation of basolateral anion uptake, paradoxically accompanied by up-regulation of apical cystic fibrosis transmembrane conductance regulator-mediated anion conductance. The latter is mediated by inhibition of Rho-kinase, which is believed to interact with actin cytoskeleton.
authors.affiliation: Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Hibino
authors.forename: Masahiro
authors.initials: M
authors.lastname: Morise
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Ito
authors.forename: Takefumi
authors.initials: T
authors.lastname: Mizutani
authors.forename: Tadakatsu
authors.initials: T
authors.lastname: Matsuno
authors.forename: Satoru
authors.initials: S
authors.lastname: Ito
authors.forename: Naozumi
authors.initials: N
authors.lastname: Hashimoto
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Sato
authors.forename: Masashi
authors.initials: M
authors.lastname: Kondo
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Imaizumi
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Hasegawa
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D027321:Anion Transport Proteins / Q000187:drug effects / Q000378:metabolism; D017920:Antiporters / Q000187:drug effects / Q000378:metabolism; D002211:Capsaicin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D017136:Ion Transport; D008564:Membrane Potentials; D026901:Membrane Transport Proteins / Q000187:drug effects* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D020545:Respiratory Mucosa / Q000187:drug effects* / Q000201:enzymology; D064606:SLC4A Proteins; D027982:Sodium-Bicarbonate Symporters / Q000187:drug effects / Q000378:metabolism; D028021:Sodium-Potassium-Chloride Symporters / Q000187:drug effects / Q000378:metabolism; D064506:Solute Carrier Family 12, Member 2; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D027321:Anion Transport Proteins; D017920:Antiporters; C505032:CFTR protein, human; D020536:Enzyme Activators; D026901:Membrane Transport Proteins; D047428:Protein Kinase Inhibitors; C578877:SLC12A2 protein, human; D064606:SLC4A Proteins; C498898:SLC4A4 protein, human; D027982:Sodium-Bicarbonate Symporters; D028021:Sodium-Potassium-Chloride Symporters; D064506:Solute Carrier Family 12, Member 2; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000242:Cyclic AMP; D054460:rho-Associated Kinases; D000262:Adenylyl Cyclases; C071423:capsazepine; D002211:Capsaicin