Importance of Transmural Pressure and Lung Volume in Evaluating Drug Effect on Pulmonary Vascular Tone

Abstract
The effect of norepinephrine (NE) on pulmonary vascular resistance (PVR) was studied in 11 thoracotomized dogs. Comparisons between the test and control states were made at corresponding average intravascular pressures in the pulmonary vascular bed and at the same airway pressure. A significant increase in PVR (P > 0.01) suggesting active vasoconstriction was found during NE administration.