Figure 2. The composite hypoxic pulmonary vasoconstrictor response (increase in pulmonary arterial pressure-left atrial pressure during hypoxia compared to normoxic values) as a function of left pulmonary blood flow in the same seven chronically instrumented dogs in the conscious state and during isoflurane anesthesia. In both the conscious and isoflurane-anesthetized states, the magnitude of the hypoxic pulmonary vasoconstrictor response was flow-dependent (P < 0.01). During isoflurane anesthesia, the hypoxic pulmonary vasoconstrictor response was attenuated (*P < 0.01) compared to the hypoxic pulmonary vasoconstrictor response measured in the conscious state.