EFFECTS OF Δ‐TRANS‐TETRAHYDROCANNABINOL ON MECHANICAL PERFORMANCE OF ISOLATED HEART MUSCLE PREPARATIONS

1 The effects of four concentrations of Δ1‐trans‐tetrahydrocannabinol (Δ1‐THC) (0.1, 1, 5 and 20 μg/ml) were compared to that of the vehicle (ethanol, 0.5 μl/ml) on the mechanical performance of isolated cardiac muscle of the cat and rat. 2 In rat isolated papillary muscles, Δ1‐THC (20 μg/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 Δ1‐THC when compared with ethanol. 4 It was concluded that Δ1‐THC in concentrations up to 20 μg/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.

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