Effects of Δ‐trans‐tetrahydrocannabinol on Mechanical Performance of Isolated Heart Muscle Preparations

1 The effects of four concentrations of delta1-trans-tetrahydrocannabinol (delta1-THC) (0.1, 1, 5 and 20 microgram/ml) were compared to that of the vehicle (ethanol, 0.5 microliter/ml) on the mechanical performance of isolated cardiac muscle of the cat and rat. 2 In rat isolated papillary muscles, delta1-THC (20 microgram/ml) caused a decline in mechanical performance (-8% in developed tension and -11% in Vmax) in contrast to the apparent lack of effect of ethanol. 3 All other parameters of mechanical performance studied in both rat and cat papillary muscles were unaffected by delta1-THC when compared with ethanol. 4 It was concluded that delta1-THC in concentrations up to 20 microgram/ml had negligible effect on contractile performance, the time course of contraction or muscle elasticity in rat and cat isolated papillary muscle preparations under the conditions studied.