Chronic lung hypoxia results in the hypoxic pulmonary hypertension, which is caused by the remodeling of peripheral pulmonary blood vessels. Vascular smooth muscle cells proliferate into the prealveolar arteries, the turnover and deposition of connective tissue proteins is increased. We observed an enhanced collagenolytic activity in the extracts from isolated peripheral lung arteries of hypoxic rats. SDS electrophoresis of collagenous proteins extracted from these vessels showed presence of the low molecular weight cleavages of collagen type I. We hypothesize that the activation of collagenolytic metalloproteinases is related to the release of reactive oxygen species, NO and products of their interaction (peroxynitrite). Collagen cleavages may stimulate mesenchymal proliferation in the vascular wall.

        Key words: pulmonary blood vessels, hypoxia, pulmonary hypertension