OBJECTIVEDuring the development of hypoxic pulmonary hypertension, the quantity of the protein and mRNA of alpha1-adrenergic receptor (alpha1-adrenergic receptor,alpha1-AR) in the lung tissue increased, while no particular reports were found about the change of the alpha1-AR subtypes during that course. The study aimed to understand the quantity and location of alpha1-AR subtypes mRNA expression in control and hypoxia rats,and the effect of phentolamine in hypoxic pulmonary hypertension.

METHODSFifty-five male Wistar rats were divided randomly into 5 groups: control group (n = 10), hypoxia 2 weeks (n = 13), hypoxia 4 weeks (n = 10), saline control group (n = 10) and hypoxia 4 weeks plus phentolamine group (n = 12). Semi-quantitative reverse transcription and polymerase chain reaction (RT-PCR) were used to examine the mRNA expression of alpha1-AR subtypes in each group. In situ hybridization was also used to detect the location of the alpha1-AR in lungs of normal rats.

RESULTS(1) The pulmonary artery pressure increased with the extension of hypoxia. (2) The results of RT-PCR showed that the mRNA expression of alpha1A-AR was the most,alpha1B-AR the second and alphaZD-AR was the least in all of the groups. (3) The expression of alpha1A-AR and alpha1B-AR mRNA increased with the extension of hypoxia, and the expressions among groups showed difference. (4) The expression of alpha1D-AR also increased with the extension of hypoxia but no difference was found among groups. (5) No difference was found in mRNA quantity of all three subtypes between phentolamine group and hypoxia saline group. (6) In situ hybridization showed that mRNA of the three alpha1-AR subtypes located mainly in the artery and venous smooth muscle cells and endothelial cells.

CONCLUSIONSThis study suggested that alpha1-AR subtypes worked in the development of hypoxia pulmonary hypertension. More research on alpha1-AR subtypes may help the clinical treatment of pulmonary hypertension.