The Effects of Cannabidiol on the Electrical and Contractile Properties of Cardio myocytes
In earlier studies, cannabidiol (CBD), a major nonpsychotropic cannabinoid found in cannabis plant, has been shown to influence cardiovascular functions under various physiological and pathological conditions. In the present study, the effects of CBD on contractility and electrical properties of rat ventricular myocytes were investigated. Video edge detection was used to measure myocyte shortening. Intracellular Ca2+ was measured in cells loaded with the fluorescent indicator fura-2 AM. CBD (1µM) caused a significant decrease in the amplitudes of electrically evoked myocyte shortening and Ca2+ transients. However, the amplitudes of caffeine-evoked Ca2+ transients and the rate of recovery of electrically evoked Ca2+ transients following caffeine application were not altered. Whole-cell patch-clamp technique was employed to investigate the effect of CBD on the characteristics of action potentials (APs) and L-type Ca2+ channels. CBD (1 µM) significantly decreased the duration of APs. Further studies on L-type Ca2+ channels indicated that CBD inhibits these channels with IC50 of 0.1µM in a voltage-independent manner.