Mechanism Of Caveolin-1 On Pulmonary Artery Constriction Induced By Various Agonists And Implications To Pulmonary Hypertension

The vascular pathological states in the pathogenesis of pulmonary hypertension(PH) owe much to an acute homeostasis imbalance of Ca2+ in pulmonary aterial smooth muscle cells(PASMCs). Caveolae is widely distributed in the vasculature, containing a variety of regulation proteins which can adjust Ca2+ concentration of the intracellular, and Cav-1(Caveolin-1) play an essential role as its signature protein. Recent studies have shown that Caveolin-1 can influence the overall structure of nonselective cation channel in a variety of cell membrane Caveolae regions. In this present study, PH rats were imitated by means of monocrotaline(MCT) intraperitoneal injection and chronic hypoxia(CH) continuous to mirror different PH characteristics. To compare the expression alterations of Cav-1 protein or m RNA in PH rats. Using Methyl-β-cyclodextrin(MβCD)destroy the integrity of Caveolae,and to preprocess of normal PASMCs with specific excitatory and inhibitory phaseolin polypeptide of Cav-1. Objective to explore the effect of Caveolin-1 on the pathogenesis of PH separately from both organ function level and cell level. In order to supply as experiment and theory foundations for PH prevention and treatment.Objective: To investigate the efforts and the pathologic physiology significance of Caveolae and Caveolin-1 in the pathogenic process of CH and MCT-induced PH, further examine the possibility pathogenesis of PH, and find new experiment and theory foundations for PH prevention and treatment.Methods: To establish PH rat models respectively by chronic hypoxic exposure(10.0%±0.5% partial pressure of oxygen) and MCT(50mg/kg) single intraperitoneal injection to SD rats for 21 days. using: ①hemodynamics and electron microscopy examination methods, measurement the variation of rats right ventricular mass index(RVMI), right ventricular systolic pressure( RVSP)and the number of Caveolae on PASMCs; ②reverse transcription polymerase chain reaction(RT-PCR) and Westernblot methods, measurement the expression levels of Cav-1 protein or m RNA in rat PAs; ③vascular circle tone detection methods, observation the influence of various agonistsinduced PAs contraction by destroying Caveolae on PASMCs with MβCD in rats; ④Fluo-3 fluorescence detection [Ca2+]i method, measurement the influence of caveolin-1 scaffolding domain peptide(CSD-p)on CPA-induced Ca2+ entry in PASMCs of control rats.Results: In comparison to the control rats, ①RVMI and RVSP were markedly elevated in MCT-treared and CH-induced PH, PAs wall thickening and stenosis, demonstrated that model rats exhibited profound PH. Meanwhile, there were more Caveolae on PASMCs of PH rats. ②the expressions of Cav-1 m RNA and protein were dramaticlly increased in PAs of PH rats; ③According to this research, voltage-dependent calcium channel( VDCC) was not closely related to Caveolae because it had minimal effect on KCl-induced PAs contraction by destroying Caveolae on PASMCs with MβCD; ④ET-1-induced PAs contraction was even bigger, indicated that SOCE up-regulation in PAs of PH rats. The changes of ET-1-induced PAs contraction effect suggested that the non-voltage-dependent calcium channel was closely correlated with the Caveolae; ⑤CPA-induced PAs contraction was greater, and MβCD had prominent effect on inhibiting PAs contraction, also indicated that SOCE up-regulation in PAs of PH rats.Results showed that store-operated calcium channel(SOCC)had intimate bonds with Caveolae and Cav-1; ⑥The inhibition of MβCD could be reversed by exogenous cholesterol in control rats, confirmed that MβCD compromise the integrity of Caveolae by depleting the cholesterol; ⑦resting [Ca2+]i, CPA-induced Ca2+ entry was increased(or decreased)in normal PASMCs which preprocess with specific excitatory(or inhibitory)phaseolin polypeptide of Cav-1, proved that SOCE was closely related with Cav-1 in PASMCs from the cell level.Conclusion: The expressions of Cav-1 m RNA and protein as well as the number of Caveolae were dramaticlly increased in PASMCs of PH rats. Cav-1 could adjust Ca2+ concentration of the intracellular, and the integrity of Caveolae was closely correlated with the non-voltage-dependent calcium channel. It turned out that the Caveolae and Cav-1 may play an important role in the pathogenesis of PH. Therefore, in the pathogenesis of PH, proper adjustments for Cav-1 expression may in favor of maintaining the dynamic equilibrium of Ca2+ in PASMCs and regressing the progress ofPH. The results of present study offer a new research idea for the precaution and treatment of PH.