[Antagonistic effects of two natural cannabinoids on the isolated heart].

Delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) have antagonistic effects on the isolated perfused heart in a Langendorff preparation. THC in concentration of 2 X 10(-6) to 10(-5)M induces an increased frequency with a maximum at 8 X 10(-6)M, and at the same time a decrease in contractile force and coronary flow. CBD at similar concentrations does not affect heart rate, while increasing contractile force and coronary flow. These effects of CBD prevail when this cannabinoid is administered simultaneously with THC.