Gardner J D, Rottman A J
Biochim Biophys Acta. 1979 Jun 12;585(2):250-65. doi: 10.1016/0304-4165(79)90025-4.
In dispersed acini from guinea pig pancreas cholera toxin bound reversibly to specific membrane binding sites to increase cellular cyclic AMP and amylase secretion. Cholera toxin did not alter outflux of 45Ca or cellular cyclic AMP. Binding of 125I-labeled cholera toxin could be detected within 5 min; however, cholera toxin did not increase cyclic AMP or amylase release until after 40 min of incubation. There was a close correlation between the dose vs. response curve for inhibition of binding of 125I-labeled cholera toxin by native toxin and the action of native toxin on cellular cyclic AMP. With different concentrations of cholera toxin, maximal stimulation of amylase release occurred when the increase in cellular cyclic AMP was approximately 35% of maximal. Cholera toxin did not alter the increase in 45Ca outflux or cellular cyclic GMP caused by cholecystokinin or carbachol but significantly augmented the increase in cellular cyclic AMP caused by secretin or vasoactive intestinal peptide. The increase in amylase secretion caused by cholera toxin plus secretin or vasoactive intestinal peptide was the same as that with cholera toxin alone. On the other hand, the increase in amylase secretion caused by cholera toxin plus cholecystokinin or carbachol was significantly greater than the sum of the increases caused by each agent alone.
在豚鼠胰腺的分散腺泡中，霍乱毒素可逆地结合到特定的膜结合位点，以增加细胞内环磷酸腺苷（cAMP）水平和淀粉酶分泌。霍乱毒素不改变45Ca外流或细胞内cAMP。在5分钟内即可检测到125I标记的霍乱毒素的结合；然而，霍乱毒素在孵育40分钟后才增加cAMP或淀粉酶释放。天然毒素对125I标记的霍乱毒素结合的抑制作用的剂量-反应曲线与天然毒素对细胞内cAMP的作用之间存在密切相关性。使用不同浓度的霍乱毒素时，当细胞内cAMP增加约为最大值的35%时，淀粉酶释放出现最大刺激。霍乱毒素不改变胆囊收缩素或卡巴胆碱引起的45Ca外流增加或细胞内环磷酸鸟苷（cGMP）水平，但显著增强促胰液素或血管活性肠肽引起的细胞内cAMP增加。霍乱毒素加促胰液素或血管活性肠肽引起的淀粉酶分泌增加与单独使用霍乱毒素时相同。另一方面，霍乱毒素加胆囊收缩素或卡巴胆碱引起的淀粉酶分泌增加明显大于每种药物单独引起的增加之和。
