Fig. 5. Proline–nitric oxide (NO) dose–response relation after preconstriction with U46619 in the conscious state and during propofol anesthesia. The vasodilator response to proline–NO is expressed as the percent decrease in preconstriction with U46619. Proline–NO–induced pulmonary vasodilation (*P < 0.05) was preserved during propofol anesthesia compared with the conscious state.