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为了探讨门静脉自发节律性收缩的起搏机制,本文应用免疫组织化学与全细胞膜片钳技术研究了家兔门静脉间质细胞(ICs)的形态及电生理学特性。经过酶解分离得到的家兔门静脉单个IC呈星状或纺锤状,自胞体向外伸出很多毛刺状突起,其酪氨酸激酶受体c-Kit染色呈阳性。应用全细胞记录模式,膜电位钳制在-60 mV,在该类细胞上记录到了自发性节律性内向电流,其频率与门静脉自发性收缩频率相近。这种电流对L型钙通道阻断剂尼卡地平不敏感,可被非选择性阳离子通道阻断剂氯化钆阻断。结果提示,在新鲜分离的家兔门静脉ICs上记录到频率与门静脉自发性收缩相近的自发性内向电流,这种内向电流可能就是启动门静脉自发性收缩的起搏电流。
In order to investigate the pacemaker mechanism of spontaneous rhythmic contraction of portal vein, immunohistochemistry and whole-cell patch clamp technique were used to study morphological and electrophysiological characteristics of rabbit portal vein interstitial cells (ICs). After enzymatic digestion of rabbit portal vein single IC was star-like or spindle-shaped, protruding from the body a lot of burr-like protrusions, the tyrosine kinase receptor c-Kit staining was positive. Using whole-cell recording mode, the membrane potential was clamped at -60 mV. Spontaneous rhythmic inward currents were recorded on these cells at frequencies similar to spontaneous contractions of the portal vein. This current is not sensitive to nicardipine, an L-type calcium channel blocker, and is blocked by gadolinium (III) chloride, a nonselective cation channel blocker. The results suggest that spontaneous inward current, which is similar to spontaneous contraction of portal vein, is recorded on freshly isolated rabbit portal vein ICs. This inward current may be the pacing current that initiates spontaneous contraction of portal vein.