交感神经损毁后大鼠心窦房结区神经递质与心电图变化的研究

CHANGES OF NEUROTRANSMITTERS IN THE SINOATRIAL NODE REGION OF THE RAT HEART AND OF ELECTROCARDIOGRAPH FOLLOWING SYMPATHECTOMY

为了探讨神经肽对心功能的调节，用６－羟多巴胺化学损毁大鼠心脏交感神经纤维后，观察了动物心电图的变化，而后用免疫组织化学法结合图像分析、放射免疫测定观测了窦房结区神经肽Ｙ（ＮＰＹ）及降钙素基因相关肽（ＣＧＲＰ）的变化；同时应用组织化学法结合图像分析、生化测定观测了窦房结区去甲肾上腺素（ＮＡ）及乙酰胆碱酯酶（ＡＣｈＥ）的变化。结果发现，静脉注射６－羟多巴胺５０ｍｇ／ｋｇ体重１周后，引起大多数动物心电图的明显改变：心率减慢，Ｐ－Ｒ间期及Ｑ－Ｔ间期延长。心脏窦房结区ＮＡ及ＮＰＹ含量明显减少，而ＡＣｈＥ活性显著增加、ＣＧＲＰ含量增加不明显。结果提示心脏交感神经纤维损毁后大鼠心电图的变化可能与心内多种神经递质的相互作用有关，神经肽在其中可能具有重要的调节作用。

To investigate the role of neuropeptides in the regulation of cardiac function, in the present study the rat ECG as recorded after chemical sympathectomy with 6 hydroxydopamine, then quantitative analysis for neuropeptide Y (NPY) and calcitonin gene related peptide (CGRP) in the sinoatrial (SA) node region of the heart was performed with immunohistochemistry, image analysis and radioimmunoassay. The levels of noradrenaline (NA) and acetylcholinesterase (AChE) in the SA node region were determined with biochemical methods. One week after intravenous administration of 50mg/kg of 6 hydroxydopamine, significant ECG changes consisting of decrease in heart rate and prolongations of the P R interval and Q T interval were observed in most rats. Treatment with 6 hydroxydopamine caused significant reduction in the levels of both NA and NPY, conversely resulted in marked increase of AChE activity and slight increase of CGRP level. The result suggested that the ECG changes following sympathectomy may be related to interactions of several intrinsic neurotransmitters, and neuropeptides might play an important modulatory role.