To determine whether hydralazine, a systemic vasodilator, exerted a similar effect on the pulmonary circulation, we studied the circulatory changes in dogs during three interventions: (a) the control state during room air ventilation; (b) during continuous hypoxic ventilation with 10% oxygen, and maintaining continuous hypoxic ventilation; and (c) after 1 mg/kg hydralazine intravenously.
