胆囊收缩素在应激时胆汁反流中的作用及其相关机制

目的证实应激过程中胆汁反流的存在,探讨胆囊收缩素八肽(CCK-8)在应激所致胆汁反流中的作用及相关机制。方法放免法检测大鼠血浆 CCK-8和胃液胆汁酸水平,测定胃液 pH值并记录胃黏膜溃疡指数;多导生理记录仪记录离体肌条收缩活动;检测 Fura-2/AM 标记的胃窦平滑肌细胞(SMC)内钙离子浓度(Ca~(2+)]i)的变化;全细胞膜片钳记录 L-型钙通道电流(I_(Ca-L))。结果与正常对照相比,应激时血浆 CCK-8从(2.23±0.88)pmol/L 到(10.80±3.82)pmol/L],胃液胆汁酸从(37.93±23.76)μmol/L 到(1316.00±197.36)μmol/L],pH 值(从1.06±1.20到5.29±1.25)和溃疡指数(从0.62±0.23到32.01±16.11)均明显增高(P<0.01);CCK-8S 显著增强胃窦和幽门肌条收缩和胃窦 SMC 的Ca~(2+)]i从(65.8±7.4)nmol/L 升至(472.1±35.6)nmol/L,P<0.01]及 I_(Ca-L)从(-56.42±6.57)pA 增至(-88.54±5.71)pA,P<0.01],但可被相应拮抗剂所抑制。结论与应激时 CCK-8升高所致的胃窦动力紊乱相关,胆汁反流存在于应激过程中,是应激性胃黏膜损伤的重要因素。

The effect and mechanism of cholecystokinin octapeptide induced-gastric dysmotility on bile regurgitation during stress

OBJECTIVE: To illustrate the existence of bile regurgitation under stress condition, and explore the possible effects and related mechanism of changes of cholecystokinin octapeptide (CCK-8) on stress-induced bile regurgitation in rats. METHODS: (1) Changes in plasma CCK-8 and gastric bile concentration were measured by using radioimmunoassay while simultaneously calculating gastric ulcer index and intragastric pH; (2) Each isolated gastric strips were suspended in a tissue chamber to record the contractile responses by polyphysiograph; (3) The responsiveness of gastric smooth muscle cells (SMCs) to sulfated cholecystokinin octapeptide (CCK-8S) were examined using fura-2-loaded microfluorimetric measurement of intracellular calcium concentration (Ca(2+)] i); (4) The current of L-type calcium channels (I(CaL)) of SMCs were recorded by patch-clamp techniques. RESULTS: (1) Compared with the normal control, plasma CCK-8 from (2.23 +/- 0.88) pmol/L to (10.80 +/- 3.82) pmol/L] and gastric bile concentration from (37.93 +/- 23.76) micromol/L to (1316.00 +/- 197.36) micromol/L] significantly increased during the stress (P < 0.01) and both simultaneously reached the peak at the time point of 2 h after stress; ulcer index (from 0.62 +/- 0.23 to 32.01 +/- 16.11) and intragastric pH (from 1.06 +/- 1.20 to 5.29 +/- 1.25) apparently increased (P < 0.01); (2) Significant changes to CCK-8S were found in the mean contractile amplitude and frequency of circular muscle and longitudinal muscle of gastric antrum and pylorus; (3) CCK-8S-evoked significant increase in Ca(2+)] i from (65.8 +/- 7.4) nmol/L to (472.1 +/- 35.6) nmol/L, P < 0.01] could be suppressed by CCK-A receptor antagonist; whereas a small but significant increases were still elicited by CCK-8S under condition of the removal of extracellular calcium; (4) CCK-8S-intensified calcium current I(Ca-L) from (-56.42 +/- 6.57) pA to (-88.54 +/- 5.71) pA, P < 0.01)] apparently inhibited by respective administration of nifedipine, Ca(2+)-ATPase inhibitors or calcium dependent chloride channel blocker (P < 0.01). CONCLUSIONS: Gastric mucosal damage induced by bile regurgitation is closely connected with gastric antrum and pylorus dysmotility evoked by CCK-8 during the stress. CCK-8S-evoked Ca(2+)] i increase in gastric antrum and pylorus SMC depends on the release of intracellular calcium stores which activates L-type voltage-dependent calcium channels through the activation of calcium dependent chloride channels.