自体移植兔静脉细胞增殖与钙激活钾通道的变化

Changes of Ca^(2+) activated potassium channels and cellular proliferation in autogenous vein grafts

目的 :研究静脉移植后钙激活钾通道 (KCa)的变化 ,并探讨其病理生理意义。方法 :将兔的双侧股静脉倒置移植于同侧股动脉缺损之间 ,采用离体血管灌流的方法 ,测定移植静脉环的张力。分别以图像分析和四唑盐(MTT)比色法检测移植静脉内膜增厚的程度以及KCa的阻断剂盐酸四乙胺 (tetraethylammoniumchloride ,TEA)对培养的家兔股静脉血管平滑肌细胞 (vascularsmoothmusclecells,VSMCs)增殖的影响。进而采用膜片钳技术记录KCa电流。结果 :移植后 1week ,静脉的收缩性和内膜相对厚度没有显著变化。静脉移植后 2weeks,收缩性和内膜相对厚度显著大于对照组 (P <0 0 5 ,n =8)。移植后 4weeks静脉的收缩性和内膜相对厚度进一步大于对照组 (P <0 0 1,n =8)。TEA(2 - 8mmol/L)显著增加培养VSMCs的MTT吸光值 ,并且有剂量依赖性 (P <0 0 5 ,n =8)。膜片钳实验结果显示 ,指令电位在 (30 - 6 0 )mV时 ,移植 (1- 4 )weeks静脉VSMCs的KCa电流密度均显著低于对照组 (P <0 0 5 ,n =5 ) ,指令电位在 2 0mV时 ,只有移植 4weeks静脉VSMCs的KCa电流密度显著低于对照组 (P <0 0 5 ,n =5 )。结论 :自体移植静脉VSMC的KCa受到抑制 ,可能是血管收缩性增强、VSMCs异常增殖的原因 ,从而导致自体移植静脉痉挛和狭窄。

AIM: To investigate changes of Ca 2+ activated potassium channels (K Ca) in autogenous vein grafts. METHODS: The contraction of venous ring was measured by means of perfusion in vitro. The intimal proliferation and proliferation of cultured smooth muscle cells (vascular smooth muscle cells, VSMCs) were observed by the means of computerised image analysis and MTT method, respectively. Furthermore, whole cell mode of patch clamp was used to record K Ca of VSMCs isolated from autogenous vein grafts. RESULTS: 1 week after transplantation there were no significant differences of contraction and intimal relative thickness between autogenous vein grafts and control. Contraction and intimal relative thickness of autogenous vein graft were significantly increased 2 weeks after transplantation (P<0.05, n=8 vs control), and they were more enhanced 4 weeks after vein transplantation (P<0.01, n=8 vs control). TEA (blocker of Ca 2+ activated potassium channels) increased MTT A 490 value of VSMCs from femoral vein in a dose-dependent manner (P<0.05, n=8). K Ca current density was significantly attenuated in VSMCs from autogenous vein grafts 1-4 weeks after transplantation (P<0.05, n=5). CONCLUSION: K Ca was inhibited in autogenous vein graft, which accounted for vasospasm and intimal proliferation.