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目的 :本实验在培养的大鼠心肌成纤维细胞 (Fb)和心肌细胞上观察了肾上腺髓质素 (AM)分泌和 5种因素对AM合成和分泌的调节 ,以阐明心肌组织AM的细胞来源。方法 :乳鼠心肌Fb和心肌细胞培养 ;放射免疫法测定AM的含量 ;放射配基结合法测定Fb和心肌细胞AM受体。结果 :心肌Fb和心肌细胞均可合成和分泌AM ,而且成纤维细胞分泌AM远高于心肌细胞 (P <0 .0 1)。肿瘤坏死因子α(tumornecrosisfactor,TNFα)、脂多糖 (lipopolysaccharide ,LPS)和碱性成纤维细胞生长因子 (bFGF)可刺激Fb和心肌细胞AM的合成与分泌。转移生长因子 β (transformationgrowthfactorβ ,TGFβ)和干扰素α(interferoneα ,IFNα)可抑制Fb和心肌细胞合成分泌AM。成纤维细胞存在着高亲和力和低亲和力两种结合位点 ,而心肌细胞仅存在着高亲和结合位点 ,心肌细胞AM受体Bmax值高于Fb (P <0 0 1)。结论 :心肌Fb也合成和分泌AM ,Fb和心肌细胞都存在AM受体。
OBJECTIVE: In this study, the secretion of adrenomedullin (AM) and the regulation of AM synthesis and secretion by five factors were observed on cultured rat cardiac fibroblasts (Fb) and cardiomyocytes to clarify the cellular origin of AM in myocardium . Methods: The myocardial Fb and cardiomyocytes were cultured in neonatal rat. Radioimmunoassay was used to determine the content of AM. The radioligand binding assay was used to determine the Fb and myocardial AM receptor. Results: Both myocardial Fb and cardiomyocytes could synthesize and secrete AM, and the secretion of AM by fibroblasts was much higher than that of cardiomyocytes (P <0.01). Tumor necrosis factor α (TNFα), lipopolysaccharide (LPS) and basic fibroblast growth factor (bFGF) stimulate the synthesis and secretion of AM in Fb and cardiomyocytes. Transforming growth factor β (TGFβ) and interferone α (IFNα) inhibit the synthesis and secretion of AM by Fb and cardiomyocytes. Fibroblasts had two binding sites with high affinity and low affinity. However, myocardial cells had only high affinity binding sites, and myocardial receptor Bmax was higher than Fb (P <0.01). CONCLUSION: Myocardial Fb also synthesizes and secrete AM receptors in AM, Fb and cardiomyocytes.