大鼠心房与心室胆碱能神经和M2受体的分布比较

目的 探讨大鼠心房，心室以及左室游离壁3层组织胆碱能神经分布及其主要靶受体-M2受体的整体表达模式和特点。方法 实验应用Kamovsky-Roots组化染色结合点计数法，免疫组化SABC法结合图像分析技术，检测胆碱能神经和M2受体的分布，并比较各部位之间神经和受体的密度差异。结果 （1）大鼠心房和心室均有胆碱能神经和M2受体的阳性染色产物，心房的胆碱能神经点计数为心室的4．6倍，M2受体免疫阳性产物面积为心室的3倍；（2）左室游离壁3层组织分析发现：中层心肌组织胆碱能神经纤维点计数明显少于心内膜层和心外膜层：左室游离壁3层心肌组织M2受体密度无显著统计学差异。结论 大鼠心房、心室肌均有胆碱能神经和M2受体，并存在明显的密度差异：左心室游离壁3层之间胆碱能神经分布有跨室壁不均一性，而M2受体密度没有明显差异。

Comparison of distribution of cholinergic nerves and M2 receptors between rat atria and ventricles

Objective To investigate the general pattern of cholinergic nerve distribution and M2 receptors in adult rat heart. Methods Karnovsky-Roots histochemical staining combining point counting method and immunochemical SABC method with image analysis were used to identify the cholinergic nerves and M2 receptors, respectively, in adult rat heart. Results Positive staining of cholinergic nerves and M2 receptors was found in all regions of the rat heart, and the point count of cholinergic nerves in the atria was 4.6 times as much as that in ventricles, and the area ofimmunoreactive substance for M2 receptors two-fold higher in the atria than in the ventricles. The point counts of the cholinergic nerves in the medial-layer myocardium were fewer than that in subepicardial and endocardial tissues of the left ventricular free wall. However, M2 receptors were comparable among the 3 layers of the left free ventricular wall. Conclusion Cholinergic nerves and M2 receptors are located in both rat atria and ventricles, but their density is much higher in the atria than in the ventricles. Transmural heterogeneity characterizes cholinergic nerve innervation in the left ventricular free wall without significant differences in M2 receptor density.