Vascular remodeling in experimentally induced subacute canine pulmonary hypertension.

We quantified in vivo pulmonary vascular remodeling in a large animal model of pulmonary hypertension (PH). In group PH (n = 6), 3 mg/kg dehydromonocrotaline (DHMC) was administered to 12-week-old beagles via a right atrial injection. Eight weeks after DHMC in group PH, pulmonary artery pressure increased significantly (P < .05) from 18 +/- 2 mm Hg at baseline to 30 +/- 4 mm Hg. Medial wall thickness and medial wall area as a percentage of total vessel diameter or area was significantly higher (P < .05) in group PH (29 +/- 9% and 48 +/- 12%) than in a control group (n = 5) (7 +/- 1% and 14 +/- 1%). Neointimal proliferation was observed in 42% of pulmonary arterioles in the PH group but never in the control group. We conclude that a single injection of DHMC in young beagles, in addition to the development of moderate degrees of PH after 8 weeks, causes significant pulmonary vascular remodeling, with features similar to those observed in patients with primary PH.