豚鼠主动脉前庭组织的自律性研究和形态学观察

A STUDY OF AUTOMATIC ACTIVITY AND MORPHOLOGY OF GUINEA-PIG AORTIC VESTIBULE

用细胞内微电极技术，对８２只豚鼠主动脉前庭的自发电活动进行了观察和分析。结果表明，１６例（１９．５％）出现自律性电活动；６１例（７４．４％）在电刺激诱导下也可出现自律性电活动。进一步观察发现，在主动脉瓣右瓣与后瓣交界以下的局部区域，可记录到有明显４相自动去极化的慢反应自律细胞样的动作电位，并可被钙通道阻滞剂Ｍｎ２＋、硝苯吡啶阻断。这一部位之外的其它大部分区域均表现为快反应动作电位。经光镜和电镜观察（ｎ＝１３），这一部位的组织与普通心室肌有明显不同，而与慢反应自律组织的结构相似。

The automatic activity of aortic vestibule was studied in 82 guinea-pig heart preparations with intracellular microelectrode. Spontaneous activity could be recorded in 16preparations (19.5 %), while in 61 preparations (74.4 %) automatic activity could be induced by electrical stimulation. Of these preparations, they were all found a very small region below the right and the poster valves, the response showed a slow and low rising phase and a marked spontaneous depolarization in phase 4. The response could be blocked by Mn2+ and nifedipine. Outside of the specialized valve region, all recorded vestibule action potentials pertain to the fast type. Light and electron microscopic examination showed that the structure of the specialized local aortic vestibule region was similar to that of ordinary myocardium possessing slow automatic activity instaed of the ordinary ventricular musculature.