The Risk of Cardiovascular Events on Cannabis' Highest Day

The electrophysiological effects of cannabidiol on action potentials and transmembrane potassium currents in rabbit and dog cardiac ventricular preparations

Cannabis use is associated with known cardiovascular side effects such as cardiac arrhythmias or even sudden cardiac death. The mechanisms behind these adverse effects are unknown. The aim of the present work was to study the cellular cardiac electrophysiological effects of cannabidiol (CBD) on action potentials and several transmembrane potassium currents, such as the rapid (I_Kr) and slow (I_Ks) delayed rectifier, the transient outward (I_to) and inward rectifier (I_K1) potassium currents in rabbit and dog cardiac preparations. CBD increased action potential duration (APD) significantly in both rabbit (from 211.7 ± 11.2. to 224.6 ± 11.4 ms, n = 8) and dog (from 215.2 ± 9.0 to 231.7 ± 4.7 ms, n = 6) ventricular papillary muscle at 5 µM concentration. CBD decreased I_Kr, I_Ks and I_to (only in dog) significantly with corresponding estimated EC₅₀ values of 4.9, 3.1 and 5 µM, respectively, without changing I_K1. Although the EC₅₀ value of CBD was found to be higher than literary C_max values after CBD smoking and oral intake, our results raise the possibility that potassium channel inhibition by lengthening cardiac repolarization might have a role in the possible proarrhythmic side effects of cannabinoids in situations where CBD metabolism and/or the repolarization reserve is impaired.

The electrophysiological effect of cannabidiol on hERG current and in guinea-pig and rabbit cardiac preparations

Cannabis use is associated with cardiovascular adverse effects ranging from arrhythmias to sudden cardiac death. The exact mechanism of action behind these activities is unknown. The aim of our work was to study the effect of cannabidiol (CBD), tetrahydrocannabinol and 11-nor-9-carboxy-tetrahydrocannabinol on cellular cardiac electrophysiological properties including ECG parameters, action potentials, hERG and I_Kr ion channels in HEK cell line and in rabbit and guinea pig cardiac preparations. CBD increased action potential duration in rabbit and guinea pig right ventricular papillary muscle at lower concentrations (1 µM, 2.5 µM and 5 µM) but did not significantly change it at 10 µM. CBD at high concentration (10 µM) decreased inward late sodium and L-type calcium currents as well. CBD inhibited hERG potassium channels with an IC₅₀ value of 2.07 µM at room temperature and delayed rectifier potassium current with 6.5 µM at 37 °C, respectively. The frequency corrected QT interval (QT_c) was significantly lengthened in anaesthetized guinea pig without significantly changing other ECG parameters. Although the IC₅₀ value of CBD was higher than literary C_max values after CBD smoking and oral intake, our results raise the possibility that hERG and potassium channel inhibition might have a role in the possible proarrhythmic adverse effects of cannabinoids in situations where metabolism of CBD impaired and/or the repolarization reserve is weakened.