AIMTo study human urotensin II (hUII) expression in intrapulmonary arteries of rats with pulmonary hypertension induced by high pulmonary blood flow and explore the role of hU II in the development of pulmonary hypertension induced by left to right shunt.

METHODSAortocaval shunting was produced for 11 weeks in rats. Pulmonary artery mean pressure (PAMP) of each rat was evaluated using right cardiac catheterization. The pulmonary vascular structural changes, including the percentage of muscularized arteries of small pulmonary vessels and relative medial thickness of intra-acinar pulmonary arteries were examined. Meanwhile, the expression of hU II by pulmonary arteries was detected by immunohistochemistry.

RESULTSAfter 11-week aortocaval shunting, PAMP was significantly increased. The percentage of muscularized arteries of small pulmonary vessels and relative medial thickness of pulmonary arteries were obviously increased in shunting rats compared with controls (P < 0.01, respectively). Meanwhile, hU II expression by pulmonary artery endothelial cells and smooth muscle cells was significantly augmented in rats of shunt group, which was positively correlated with PAMP and the structural changes in pulmonary arteries.

CONCLUSIONThe up-regulation of hU II in pulmonary arteries might be involved in the development of pulmonary vascular structural remodeling and pulmonary hypertension induced by high pulmonary blood flow.