摘要
本文使用Fura-2做为细胞内钙离子荧光指示剂,在大白鼠胰腺分离细胞观察缩胆囊素和乙酰胆碱对细胞内钙离子的影响及其相互作用.结果表明1nmol/L缩胆囊素和lmmol/L乙酰胆碱分别使细胞内钙离子浓度从基础水平的122±8nmol/L增高至360±32nmol/L和380±20nmol/L,半最大有效浓度分别为0.45nmol/L及54μmol/L。不同剂量的缩胆囊素和乙酰胆碱彼此不同程度抑制对方的作用,后加入的试剂提高细胞内钙离子浓度的幅度与先加入的试剂所引起的增加幅度成反比,加入各自相应的受体拮抗剂可使细胞恢复对另一激素(蛙皮素)刺激的反应。说明了缩胆囊素受体和胆碱能受体的相互调节影响细胞内钙离子的活动.加入受体拮抗剂后,细胞恢复反应过程中的时间动力学改变可能与受体阻滞后钙离子通道关闭的程度和时间有关.
In isolated rat pancreatic acinar cells, cholecystokinin octapeptide (cck-8) and carbachol increased free cytosolic calcium calcium concentration [Ca^(2+)]i)(as measured by the fluorescent probe fura 2). The maximal [Ca^(2+)] i values were 360±32 nmol/L for 1 nmol/L cck-8 stimulation and 380±20nmol/L for 1 mmol/L carbachol. Basal [Ca^(2+)]i level was 122±8 nmol/L. The action of cck-8 and carbachol were in a concentration-dependent manner with apparent half maximal concentration of 0.45 nmol/L and 54 μmol/L, respectively. Furthermore each agent inhibited the subsequent response to another in a competitive manner. The heterologous tachyphylaxis seen after a prior exposure to cck-8 or carbachol was progressively reversed by subsequent addition of its antagonists, CR1049 or atropine. The chronokinetics were consistent with a reloading rate being dependent on the rate and/or the efficacy of closure of secretagogue-dependent intracellular calcium channels upon receptor deactivation.
关键词
胰腺
缩胆囊素
乙酰胆碱
钙
PANCREAS/metabolismCALCIUM/metabolismCHOLECYSTOKININ/pharmacodynamicsACETYLCHOLINE/pharmacodynamicsDRUG ANTAGONlSM
