Figure 4. Pulmonary vascular pressure gradient (pulmonary arterial pressure-left atrial pressure: PAP-LAP) at left pulmonary blood flows of 40, 50, and 60 ml [middle dot] min^-1[middle dot] kg^-1during normotension and hypotension in eight intact conscious dogs. The PAP-LAP gradient at each value of left pulmonary blood flow was calculated from regression parameters obtained from each experiment. Hypotension increased (*P < 0.05) PAP-LAP compared with values measured during normotension; i.e., hypotension resulted in pulmonary vasoconstriction in intact conscious dogs.