Fig. 2.
Prevention of the respiratory-depressant effects of heroin in four monkeys. Heroin dose-effect curves were determined at various times after the administration of MCAM (upper) or naltrexone (lower). Data from OL, ME, CE, and GI are shown in the upper panel, whereas data from OL, ME, SC, and GI are shown in the bottom panel. Heroin doses were normalized across animals such that dose X is the smallest dose of heroin that decreased VE to <70% of control (see Fig. 1 for individual doses). Abscissae: normalized heroin dose. Ordinates: minute volume (VE) expressed as a percentage of control.