| Objective:The reduce of Nitric oxide (NO) is one of the most important inducements in the pathogenesis of cerebral vasospasm (CVS) after subarachnoid hemorrhage (SAH), Gap junction (GJ) participates in the pathological processes of cerebrovascular diseases and may play an important role. The aim of this study is to investigate the expression of Connexin43 and the role of GJ in NO-relieved CVS. It is expected to provide a basic evidence for the important role of GJ in CVS, and novel approaches for the management of CVS may be achieved,and expected to supply a possible key for clinic therapy of CVS .Methods:1. Isometric Tension: The rabbits were anesthetized and euthanatized by exsanguinations. The BAs were removed from the dissociative brain stems and cut into 3-4mm rings. different concentrations of PGF2a,different concentrations of DETA-NO,different concentrations of GJ blocker carbenoxolone,sGC inhibitor ODQ were used to incubated the vitro rings respectively, and the tension was recorded continuously with a force displacement transducer.2. The BA strips with treatments in vitro: The rabbits were anesthetized and euthanatized by exsanguinations. The BAs were removed from the dissociative brain stems and cut into intact strips. different concentrations of PGF2a,different concentrations of DETA-NO,different concentrations of GJ blocker carbenoxolone,sGC inhibitor ODQ were used to incubated the strips respectively, and western blotting was used for detecting the change of Cx43 protein expression in the different strips.3. The rabbit double-hemorrhage model of SAH was established in vivo and then disposal them with drugs: All animals were anesthetized by pentobarbital. CVS was then induced by intracisternal injection of autologous arterial blood on Day0 and Day2. NO donator DETA-NO, sGC inhibitor ODQ were administered in a 2-ml intrathecal injection via the cisterna magna on Day7.The change of the basilar artery (BA) diameter of rabbits was measured with the aid of angiography on Day0 and Day7. Western blotting was used for the change of Cx43 protein expression in the BAs.Results:1. Different concentrations (0.3-30umol/L) of PGF2a could produced concentration-dependent contractions, the isolated rings were contracted obviously by 10umol/L PGF2a . DETA-NO can obviously reverse the contractions in the vitro basilar artery rings caused by PGF2a , Different concentrations (0.3-100μmol/L) of DETA-NO produced a potent and concentration-dependent relaxation of vascular rings. The sGC inhibitor ODQ blocked the relaxation of DETA-NO effectively. Gap junction blockers CBX blocked the contractions of PGF2a effectively.2. When the BA strips were treated with different PGF2a (0.3-30μmol/L), the total protein level of Cx43 increased gradually in a concentration-dependent fashion. DETA-NO, which concentrated extent was from 0.3μmol/L to 100μmol/L, could depressed the protein level of Cx43 induced by PGF2a; ODQ could effectively inhibit the depression of the protein of Cx43 induced by DETA-NO.GJ blocker could obviously depressed the protein level of Cx43 was induced by PGF2a.3. The rabbit double-hemorrhage model of SAH was established successfully. Brain angiographies on day7 showed severe narrowing of the BAs. DETA-NO could obviously reverse the spasm and ODQ could reduce the relaxed effection induced by DETA-NO. The total protein level of Cx43 on day7 was significantly higher compared with that in normal control group; the total protein of Cx43 on day7 treated with DETA-NO was significantly lower than that in SAH-only group; sGC inhibitor ODQ could inhibit the depression of the total protein level of Cx43 induced by DETA-NO.Conclusion:1.GJ played an important role in the cerebrovascular contraction induced by PGF2a.The basilar arteries were obviously contracted treated by PGF2a in a concentration-dependent fashion. Meanwhile, the total protein expression level of Cx43 in cerebrovascular cells treated by PGF2a was obviously up-regulated in a concentration-dependent fashion. GJ inhibitor CBX could effectiously relief the cerebrovascular contraction and down-regulated the total protein expression level of Cx43 in cerebrovascular cells induced by PGF2a .2. GJ probably played an important role in the process when NO relieved the contraction of cerebrovascular. Exogenous NO could obviously relieved CVS induced by SAH and the cerebrovascular contraction induced by PGF2a , and Low NO could effectively down-regulate the total protein expression level of Cx43 in cerebrovascular cells. The molecule mechanism of NO-cGMP probably played an important role in the process when NO relieved the cerebrovascular contraction and down-regulated the protein expression level of Cx43 in cerebrovascular cells .
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