K物质在大鼠心脏内的分布及其对心血管活动的作用

DISTRIBUTION OF SUBSTANCE K IN THE RAT HEART AND ITS CARDIOVASCULAR EFFECTS

本工作应用特异性K物质放射免疫分析法测定了大鼠心脏的K物质样免疫活性,心房和心室含量分别为19.9±3.5和4.1±0.8pmol/g组织。心脏内的K物质样免疫活性物质主要以单一分子形式存在。用免疫组织化学方法证明K物质免疫活性存在于心脏神经纤维内。大鼠心肌杂交细胞株(CP8401)细胞上含有K物质特异性结合部位,KD为1.61×10^(-10)mol/L,Bmax为8.08×10^(-12)mol/L。用心肌杂交细胞和离体心脏进行体外实验,证明K物质可释放ANF,这种释放可为速激肽受体拮抗剂[D-Pro^2,D-Trp^(7,9)]-SP部份抑制。给麻醉大鼠静脉注射K物质可引起血压降低、心率加快、左心室内压和收缩速度下降。这一作用亦可被[D-Pro^2,D-Trp^(7,9)]-SP所部份抑制。应用大鼠离体灌流心脏模型,发现K物质可升高心脏灌流压、左心室收缩期峰压、左心室内压最大上升速率和加快心率、具有正性变时和变力性作用。 本工作提示,K物质存在于心脏神经纤维内,在心肌细胞上具有K物质的特异性结合位点。K物质可促进心肌细胞释放心钠素,并可调节心脏的功能。

The present work was to investigate the distribution of Substance K (SK) in the rat heart and its cardiovascular effects. The content of SK-like immunoreactive material (SKLI), determined by using specific radioimmunoassay, was higher in the atrium (19.9±3.5pmol/g tissue) than in the ventricle (4.1±0.8 pmol/g tissue). SKLI in the heart existed in the nerves fibers and its molecular form was identical with synthetic SK. There were high affinity binding sites of SK on the cardiohybricyte CP 8401: KD=0.161nmol/L, Bmax=8.08pmol/L. SK stimulated the release of ANF from the cardiohybricytes and from the isolated rat atria. Furthermore, SK injected intravenously induced a hypotensive effect in rats, and decrcased left ventricle end systolic pressure (LVESP), ±LVdp/dt_(max), as well as slightly increased heart rate (HR). In isolated Langendorff perfusion heart of rat, SK increased HR, LVdp/dt_(max), left ventricle peak systolic pressure (LVPSP) and perfusion pressure (PP). These effects of SK were inhibitod by a tachykinin receptor antagonist, (D-Pro^2, D-Trp^(7,9)) -SP.These findings suggest that SK exist in the heart and might be able to bind with its specific binding sites on the cardiocytes, thus inducing the release of ANF from the atrium and regulating cardiovascular functions.