Tolerance to the cardiovascular effects of delta9-tetrahydrocannabinol in the rat.
1. Daily intraperitoneal injections of delta9-tetrahydrocannabinol (delta9-THC, 10 mg/kg) resulted in tolerance to the effects of the cannabinoid on body weight and body temperature within 1-2 weeks of treatment. 2. Tolerance failed to develop to the suppression of spontaneous motor activity produced by delta9-THC during 28 days of treatment with the cannabinoid (10 mg/kg, i.p. per day). 3. Following treatment with vehicle for 28 days, intravenous administration of delta9-THC in anaesthetized rats produced a transient pressor response followed by a sustained hypotension and bradycardia. 4. Tolerance to the hypotensive and negative chronotropic responses to intravenous delta9-THC was readily apparent in animals which had received daily intraperitoneal injections of delta9-THC (10 mg/kg) for 28 days. 5. Tolerance failed to develop to the pressor actions of intravenous delta9-THC after 28 days of preptreatment. 6. There was no difference in the pressor response to intravenous noradrenaline in vehicle-treated animals (1.0 ml/kg, i.p., per day for 28 days) and delta9-THC-treated animals (10 mg/kg, i.p., per day for 28 days).
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001831:Body Temperature / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D013759:Dronabinol / Q000494:pharmacology*; D004361:Drug Tolerance; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D013997:Time Factors
D013759:Dronabinol; D009638:Norepinephrine