title: (Endo)cannabinoids mediate different Ca2+ entry mechanisms in human bronchial epithelial cells.
abstract: In human bronchial epithelial (16HBE14o(-)) cells, CB(1) and CB(2) cannabinoid receptors are present, and their activation by the endocannabinoid virodhamine and the synthetic non-selective receptor agonist CP55,940 inhibits adenylyl cyclase and cellular interleukin-8 release. Here, we analyzed changes in intracellular calcium ([Ca2+](i)) evoked by Delta(9)-tetrahydrocannabinol (Delta(9)-THC), CP55,940, and virodhamine in 16HBE14o(-) cells. Delta(9)-THC induced [Ca2+](i) increase and a large transient [Ca2+](i) mobilization, the latter probably reflecting store-depletion-driven capacitative Ca2+ entry (CCE). In contrast, CP55,940 induced a rather moderate Ca2+ influx and a sustained [Ca2+](i) mobilization. CP55,940-induced Ca2+ influx was inhibited by Ni2+, indicating CCE, possibly mediated by transient receptor potential channel TRPC1, the mRNA of which is expressed in 16HBE14o(-) cells. CP55,940-induced calcium alterations were mimicked by virodhamine concentrations below 30 microM. Interestingly, higher virodhamine induced an additional Ca2+ entry, insensitive to Ni2+, but sensitive to the TRPV1 antagonist capsazepine, the TRPV1-TRPV4 inhibitor ruthenium red, and the non-CCE (NCCE) inhibitors La3+ and Gd3+. Such pharmacological profile is supported by the presence of TRPV1, TRPV4, and TRPC6 mRNAs as well as TRPV1 and TRPC6 proteins in 16HBE14o(-) cells. Cannabinoid receptor antagonists increased virodhamine-induced Ca2+ entry. Virodhamine also enhanced arachidonic acid release, which was insensitive to cannabinoid receptor antagonism, but sensitive to the phospholipase A(2) inhibitor quinacrine, and to capsazepine. Arachidonic acid induced [Ca2+](i) increase similar to virodhamine. Collectively, these observations suggest that [Ca2+](i) alterations induced by Delta(9)-THC, CP55,940 and by low concentrations of virodhamine involve mobilization and subsequent CCE mechanisms, whereas such responses by high virodhamine concentrations involve NCCE pathways.
authors.affiliation: Department of Molecular Pharmacology, University Centre for Pharmacy, University of Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands, e.gkoumassi@gmail.com
authors.forename: Effimia
authors.initials: E
authors.lastname: Gkoumassi
authors.forename: Bart G J
authors.initials: BG
authors.lastname: Dekkers
authors.forename: Melloney J
authors.initials: MJ
authors.lastname: Dröge
authors.forename: Carolina R S
authors.initials: CR
authors.lastname: Elzinga
authors.forename: Rutger E
authors.initials: RE
authors.lastname: Hasenbosch
authors.forename: Herman
authors.initials: H
authors.lastname: Meurs
authors.forename: S Adriaan
authors.initials: SA
authors.lastname: Nelemans
authors.forename: Martina
authors.initials: M
authors.lastname: Schmidt
authors.forename: Johan
authors.initials: J
authors.lastname: Zaagsma
mesh_terms: D016718:Arachidonic Acid / Q000378:metabolism; D001095:Arachidonic Acids / Q000008:administration & dosage / Q000494:pharmacology; D001980:Bronchi / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D063385:Cannabinoid Receptor Modulators / Q000008:administration & dosage / Q000494:pharmacology*; D002186:Cannabinoids / Q000008:administration & dosage / Q000494:pharmacology*; D002460:Cell Line; D003511:Cyclohexanols / Q000008:administration & dosage / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D013759:Dronabinol / Q000008:administration & dosage / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D012333:RNA, Messenger / Q000378:metabolism; D050052:TRPC Cation Channels / Q000378:metabolism
chemical_list: D001095:Arachidonic Acids; D063385:Cannabinoid Receptor Modulators; D002186:Cannabinoids; D003511:Cyclohexanols; D012333:RNA, Messenger; D050052:TRPC Cation Channels; C096351:transient receptor potential cation channel, subfamily C, member 1; C456739:virodhamine; D016718:Arachidonic Acid; D013759:Dronabinol; C054649:3-(2-hydroxy-4-(1,1-dimethylheptyl)phenyl)-4-(3-hydroxypropyl)cyclohexanol; D002118:Calcium