Relation between redox state and secretory response to brain-gut peptides

用Fura-2荧光显微分光光度法测定了胆囊收缩素（CCK-8）C端八肽连续刺激胰腺腺泡单个细胞时胞浆内钙离子浓度[Ca^2+] i的变化。在显微荧光分光光度法之前，在Nomarski微分干涉对比光学系统下检查相同的细胞。区域形态差异可以解决，只要，顶端的一半腺泡细胞含有大量的酶原颗粒（ZG区域），而基础的一半出现明确的几个颗粒（内质网区域; ER区域）。当用30 pM CCK-8持续刺激腺泡细胞时，[Ca^<2 +>]_i在ER区出现振荡，而在ZG区则出现短暂的升高。[Ca^<2+>] i的振荡变化由三个部分组成：1）初始瞬时升高; 2）在无Ca^<2+>溶液灌流过程中，[Ca^<2+>] i随CCK-8浓度的增加而逐渐下降。用100 pM CCK-8连续刺激腺泡细胞，可观察到胞浆内[Ca^<2+>]_i的一次短暂升高，但无随后的振荡。fura-2 AM（10 μ m）对30 pM CCK-8的分泌反应无明显影响，但对100 pM CCK-8的分泌反应有明显抑制作用。结果表明，CCK-8诱导的胰腺腺泡细胞内[Ca^<2+>] i的振荡性变化可能在刺激-分泌偶联中起重要作用。

Microspectrofluorimetry with fura-2 was utilized to monitor cytosolic concentration of calcium ion, [Ca^<2+>]_i, in single cells of the isolated pancreatic acini during continuous stimulation with C-terminal octapeptide of cholecystokinin (CCK-8). Prior to the microspectrofluorimtry, the same cells were examined under the Nomarski differential interference contrast optical system. Regional morphological differences could be resolved, insofar as, the apical half of an acinar cell contained a large number of zymogen granules (ZG region), whereas the basal half appeared clear with few granulation (region of endoplasmic reticulum; ER region). When acinar cells were continuously stimulated with 30pM CCK-8, which is known to cause sustained increase in amylase release from pancreatic acini, oscillation of [Ca^<2+>]_i was usually observed in the ER region, whereas a single transient increase in [Ca^<2+>]_i was usually detected in the ZG region. The oscillatory change in [Ca^<2+>]_i consisted of three components: 1) an initial transient increase flowed by 2) a gradual decline, upon which 30 pM CCK-8 during perfusion with a Ca^<2+>-free solution, the initial transient increase in [Ca^<2+>]_i remained but the secondary oscillations were abolished. A single transient increase in [Ca^<2+>]_i without any subsequent oscillation was observed when the acinar cells were continuously stimulated with 100pM CCK-8. Secretory responses of acinar cells to 30pM CCK-8 were not interfered with fura-2 AM (10mum), but these to 100 pM CCK-8 were significantly inhibited with fura-2 AM. These results show that the CCK-8-induced oscillatory changes in [Ca^<2+>]_i may play a significant role in the stimulus-secretion coupling in the pancreatic acinar cell.