Fine structural alterations of bovine peripheral pulmonary arteries in hypoxia-induced hypertension.

Cellular alterations of the distal bovine pulmonary arteries in hypoxia-induced pulmonary hypertension were studied. These lesions were related to pulmonary hemodynamic changes and contrasted to the cellular response observed in hyperkinetic pulmonary and systemic hypertension as well as other forms of vascular injury. Medial thickening and mild adventitial proliferation with an absence of intimal proliferative lesions related to a progressive increase in mean pulmonary arterial pressure and pulmonary vascular resistance were observed. Smooth muscle and endothelial cells exhibited distinct degenerative alterations in response to the maintained hypertensive state resulting from the lowered alveolar oxygen tension.