Expression of urotensin II in sprague-dawley rat with monocrotaline-induced pulmonary hypertension

Objective To study the expression of urotensin Ⅱ (U Ⅱ ) in plasma and pulmonary artery of SD rats with monocrotaline(MCT)-induced pulmonary hypertension. Methods Totally 30 male SD rats were divided into the MCT and control group, with 15 rats in each group. Rat model of pulmonary hypertension were established by a single subcutaneous injection of 60 mg/kg MCT, the same volume of saline was used in control group instead of MCT. The rats were killed and the blood and lungs were taken at the end of the third week respectively after the models were established. The expression of U Ⅱ in plasma was measured by radioimmunoassay, while the expression of U Ⅱ protein in pulmonary artery tissues was observed by immunohistochemistry and the image was analyzed. Results U Ⅱ concentrations in plasma were highly increased in rats with MCT-induced pulmonary hypertension than those of the controls( P ＜0.01), while immunohistochemistry tests also showed the average value of integral light density of U Ⅱ protein in pulmonary artery tissues were significantly higher than those of the controls( P ＜0.01). Furthermore, there were regional differences in the efficacy of U Ⅱ , with a progressive increase in the maximum contraction from proximal to distal pulmonary artery. Conclusions Concentration of U Ⅱ in plasma and expression intensity in pulmonary arteries were highly increased in SD rat with MCT-induced pulmonary hypertension, suggesting its potential role in the process of pulmonary hypertension. Key words: Urotensin Ⅱ; Monocrotaline; Pulmonary hypertension; mmunohistochemistry; Sprague-Dawley rat