Cannabinoid CB1 receptor of cat cerebral arterial muscle functions to inhibit L-type Ca2+ channel current. Am J Physiol 1999 Jun;276(6):H2085-93
Date
06/11/1999Pubmed ID
10362691DOI
10.1152/ajpheart.1999.276.6.H2085Scopus ID
2-s2.0-0033002210 (requires institutional sign-in at Scopus site) 239 CitationsAbstract
The CB1 subtype of the cannabinoid receptor is present on neurons in the brain and mediates the perceptual effects of Delta9-tetrahydrocannabinol and other cannabinoids. We found that cat cerebral arterial smooth muscle cells (VSMC) contain the protein for the CB1 receptor and express a cDNA that has >98% amino acid homology to the CB1 cDNA expressed in rat and human neurons. Activation of the CB1 cannabinoid receptor has been shown to decrease the opening of N-type voltage-gated Ca2+ channels in neurons through a pertussis toxin-sensitive GTP-binding protein. In the present study we tested the hypothesis that activation of the cannabinoid CB1 receptor in cerebral VSMC inhibits voltage-gated Ca2+ channels and results in cerebral vasodilation. The predominant Ca2+ current identified in cat cerebral VSMC is a voltage-gated, dihydropyridine-sensitive, L-type Ca2+ current. The cannabimimetic drug WIN-55,212-2 (10-100 nM) induced concentration-dependent inhibition of peak L-type Ca2+ current, which reached a maximum of 82 +/- 4% at 100 nM (n = 14). This effect was mimicked by the putative endogenous CB1-receptor agonist anandamide, which produced a concentration-related reduction of peak L-type Ca2+ current with a maximum inhibition (at 300 nM) of 39 +/- 4% (n = 12). The inhibitory effects of both ligands on peak L-type Ca2+ currents were abolished by pertussis toxin pretreatment and application of the CB1-receptor antagonist SR-141716A (100 nM, n = 5). Both WIN-55,212-2 and anandamide produced concentration-dependent relaxation of preconstricted cerebral arterial segments that was abolished by SR-141716A. These results indicate that the CB1 receptor is expressed in cat cerebral VSMC and that the cerebral vasculature is one of the targets for endogenous cannabinoids. These findings suggest that the CB1 receptor and its endogenous ligand may play a fundamental role in the regulation of cerebral arterial tone and reactivity by modulating the influx of Ca2+ through L-type Ca2+ channels.
Author List
Gebremedhin D, Lange AR, Campbell WB, Hillard CJ, Harder DRAuthors
William B. Campbell PhD Professor in the Pharmacology and Toxicology department at Medical College of WisconsinCecilia J. Hillard PhD Associate Dean, Center Director, Professor in the Pharmacology and Toxicology department at Medical College of Wisconsin
MESH terms used to index this publication - Major topics in bold
Amino Acid SequenceAnimals
Arachidonic Acids
Benzoxazines
Calcium Channels
Calcium Channels, L-Type
Cats
Cerebral Arteries
Electric Conductivity
Endocannabinoids
Female
Male
Molecular Sequence Data
Morpholines
Muscle, Smooth, Vascular
Naphthalenes
Polyunsaturated Alkamides
RNA, Messenger
Receptors, Cannabinoid
Receptors, Drug
Vasomotor System
