A method for exposing primates to marihuana smoke that stimulates the method used by human marihuana smokers

A method was developed for exposing rhesus monkeys to marihuana smoke under conditions simulating those used by human marihuana smokers. An ADL II smoking machine was used to generate puffs of smoke of constant volume from marihuana or placebo cigarettes at a constant rate. The outlet of the smoking machine was connected by Tygon tubing to an airtight face mask covering the monkey's nose and mouth. The monkey was seated in an airtight Plexiglas chamber with only its head protruding. When a puff of smoke was generated, a vacuum was imposed on the chamber causing the monkey to inhale deeply and hold its breath. After 6 seconds, the vacuum was removed and the monkey was allowed to exhale and breathe fresh air freely until the next puff. Delivery of smoke to the monkey by this method was more efficient than allowing the monkey to voluntarily inhale the smoke. The method was used in acute dose-effect experiments and, subsequently, in long-term experiments. It may be useful with other animal species and for efficiently delivering other airborne substances of abuse.