Fig. 3. Composite left pulmonary vascular pressure–flow (LPQ) plots at baseline, after matched preconstriction with U46619, and during administration of acetylcholine (10 μg · kg−1· min−1, intravenously) in (A ) the conscious state and (B ) during propofol anesthesia. This dose of acetylcholine caused a rightward shift (*P < 0.05) in the LPQ relation, indicating pulmonary vasodilation. The magnitude of the vasodilator response to acetylcholine was attenuated (P < 0.05) during propofol anesthesia.