Antihypertensive effects of delta9-tetrahydrocannabinol.

Repeated oral administration of delta9-tetrahydrocannabinol (delta9-THC, 25 mg/kg) reduced systolic blood pressure in conscious spontaneously hypertensive rats. Tolerance to the antihypertensive actions of delta9-THC failed to develop during the 10-day treatment period. The failure of delta9-THC to alter blood pressure in normotensive rats suggests that the hypotensive action of delta9-THC is dependent, in part, on baseline blood pressure.