The Molecular Mechanisms Of Hypoxia Pulmonary Hypertension Study The Changes In The Adrenergic Receptor Gene Transcription Activity

Chronic obstructive puhnonary disease is a common disease which severely threaten the health of individuals in our country. Sustained constriction of pulmonary arterioles and the remodelling of vascular structures induced by hypoxia, caused by airway obstruction, are two important aspects contributed in the pathogenesis and development of pulmonary hypertension. Our previous studies showed that in hypoxic puhnonary hypertension rat, α-adrenergic receptor (α-AR) inceased and β₂-adrenergic receptor (β₂-AR) decreased in puhnonary arterioles and the response of puhnonary arteries to noradrenaline was enhanced. The antogonists of α-AR and the agonists of β-AR are effective in reduction of the puhnonary hypertension. It was also found that hypoxia could directly induce the prolifications of cultured puhnonary vascular smooth muscle cells in vitro. α₁-AR agonist could enhance this prolification. Results implied that adrenergic recepor played a role in this process. In vivo a-AR antogonists could prevent the puhnonary arteriolar wall from thickness. Molecular biological research showed that α₁-AR gene expression increased and β₂-AR gene expression decreased in puhnonary tissue and arterioles in hypoxic rat. Hypoxia also induced high expression of α₁ and β₂ AR genes in puhnonary arterial smooth muscle cells (PASMC). When salbutamol and prazosin was used to reduce puhnonary hypertension, salbutamol showed the ability to prevent β₂AR mRNA from decreasing, and prazosin inhibited α₁AR mRNA expression, but not to β₂AR mRNA expression.Based on those experiments, we designed following experiments, 1. Effects of hypoxia and salbutamol on puhnonary hypertension and pulmonary vascular remodelling in rats. 2. Puhnonary vascular α_1B and β₂ gene expression levels responsed to hypoxia and salbutamol using in situ hybridization. 3. Effect of hypoxia, prazosin and salbutamol on α_1B and β₂ AR gene tanscription activity in cultured bovine puhnonary vascular smooth muscle cells. For the necessary of those molecular biologic research, we carried out the subcloning of α_1B and β₂ cDNA, and established the methods of generating digoxigenin-lablelled single-stranded probes and nuclear run-on transcription assay.