(Endo)cannabinoids mediate different Ca2+ entry mechanisms in human bronchial epithelial cells

Naunyn Schmiedebergs Arch Pharmacol. 2009 Jul;380(1):67-77. doi: 10.1007/s00210-009-0406-z. Epub 2009 Mar 3.

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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arachidonic Acid / metabolism
  • Arachidonic Acids / administration & dosage
  • Arachidonic Acids / pharmacology
  • Bronchi / cytology
  • Bronchi / drug effects
  • Bronchi / metabolism
  • Calcium / metabolism*
  • Cannabinoid Receptor Modulators / administration & dosage
  • Cannabinoid Receptor Modulators / pharmacology*
  • Cannabinoids / administration & dosage
  • Cannabinoids / pharmacology*
  • Cell Line
  • Cyclohexanols / administration & dosage
  • Cyclohexanols / pharmacology
  • Dose-Response Relationship, Drug
  • Dronabinol / administration & dosage
  • Dronabinol / pharmacology
  • Epithelial Cells / drug effects
  • Epithelial Cells / metabolism
  • Humans
  • RNA, Messenger / metabolism
  • TRPC Cation Channels / metabolism

Substances

  • Arachidonic Acids
  • Cannabinoid Receptor Modulators
  • Cannabinoids
  • Cyclohexanols
  • RNA, Messenger
  • TRPC Cation Channels
  • transient receptor potential cation channel, subfamily C, member 1
  • virodhamine
  • Arachidonic Acid
  • Dronabinol
  • 3-(2-hydroxy-4-(1,1-dimethylheptyl)phenyl)-4-(3-hydroxypropyl)cyclohexanol
  • Calcium