Cannabidiol selectively inhibits the contraction of rat small resistance arteries: Possible role for CGRP and voltage-gated calcium channels

Abstract

The pharmacology of cannabidiol, the non-psychoactive major component of Cannabis sativa, is of growing interest as it becomes more widely prescribed. This study aimed to examine the effects of cannabidiol on a wide range of contractile agents in rat small resistance arteries, in comparison with large arteries, and to explore its mechanism of action. The vascular actions of cannabidiol were also contrasted with effects on the contractions of bronchial, urogenital, cardiac and skeletal muscles. Isolated small or large arteries were incubated with cannabidiol (0.3-3 μM) or vehicle and concentration-contraction response curves were completed to various agents, including endothelin-1, arginine vasopressin, methoxamine, 5-HT, α-methyl 5-HT and U46619. In small arteries, the effects of cannabidiol were tested in the presence of antagonists of CB₁ or CB₂ receptors, calcitonin gene-related peptide (CGRP), nitric oxide synthase, cyclooxygenase, PPARγ or a combination. The role of L-type voltage-operated calcium channels was also assessed. Cannabidiol 1-3 μM significantly inhibited the contraction of small resistance arteries to all tested agents through a combination of mechanisms that include CGRP and L-type calcium channels. However, large arteries were insensitive to cannabidiol. Cannabidiol (10-100 μM) was largely without effect in bronchi, atria and hemidiaphragm, but 100 μM attenuated maximum contractions in vasa deferentia. Cannabidiol's effects in the clinical range (1-3 μM) appear to be specific to small resistance arteries. This high sensitivity of the resistance arterial circulation to cannabidiol may offer a therapeutic opportunity in peripheral vascular disease that excludes off-target sites such as the heart and non-vascular smooth muscle.

Keywords: (−)-cannabidiol (PubChem CID: 644019); (−)-isoproterenol (+)-bitartrate (PubChem CID: 349817090); (−)-noradrenaline bitartrate (PubChem CID: 297812); 2-chloro-5-nitro-N-phenylbenzamide (GW9662, PubChem CID: 644213); 5-hydroxytryptamine creatinine sulfate (PubChem CID: 164531); 8-methyl-N-vanillyl-6-nonenamide (capsaicin, PubChem CID: 1548943); Acetylcholine bromide (PubChem CID: 65551); BIBN 4096 (olcegepant, PubChem CID: 6918509); Bay K8644 (PubChem CID: 2303); Calcitonin gene-related peptide; Cannabidiol; L-nitro arginine methyl ester (PubChem CID: 135193); L-type voltage-gated calcium channels; O-1918 (PubChem CID: 40469923); SR144528 (PubChem CID: 3081355); Small mesenteric arteries; U46619 (PubChem CID: 16219283); Vascular smooth muscle contraction; arginine-vasopressin (PubChem CID: 644077); calcitonin gene-related peptide (PubChem CID: 90479760); carbamoylcholine chloride (carbachol, PubChem CID: 5831); endothelin-1 (PubChem CID: 16132423); indomethacin (PubChem CID: 3715); methoxamine hydrochloride (PubChem CID: 6081); rimonabant (SR141716, PubChem CID: 104850); α-methyl-5-hydroxytryptamine maleate (PubChem CID: 9922558).