Malhotra R, Singh L, Eng J, Raufman J P
Department of Medicine, State University of New York-Health Science Center, Brooklyn 11203-2098.
Regul Pept. 1992 Sep 22;41(2):149-56. doi: 10.1016/0167-0115(92)90044-u.
We examined the actions of exendin-4, a new peptide isolated from Heloderma suspectum venom, on dispersed acini from rat pancreas. Exendin-4 caused a 3-fold increase in cAMP but did not alter cellular calcium concentration. Exendin-4-induced increases in cAMP were inhibited by an exendin-receptor antagonist, exendin (9-39)NH2, but not by VIP-receptor antagonists. Whereas up to 1 microM exendin-4 alone did not alter amylase release, potentiation of enzyme release was observed when the peptide (greater than 30 pM) was combined with cholecystokinin. Potentiation of amylase release was also observed when exendin-4 was combined with carbamylcholine, bombesin or a calcium ionophore, A23187. These results indicate that stimulation of exendin receptors on rat pancreatic acini causes an increase in cellular cAMP. Although this increase in cAMP alone does not result in amylase release, combination of exendin-4 with agents that increase cell calcium results in potentiation of amylase release.
我们研究了从希拉毒蜥毒液中分离出的一种新肽艾塞那肽-4对大鼠胰腺分散腺泡的作用。艾塞那肽-4使环磷酸腺苷（cAMP）增加了3倍，但未改变细胞内钙浓度。艾塞那肽-4诱导的cAMP增加被艾塞那肽受体拮抗剂艾塞那肽（9 - 39）NH2抑制，但未被血管活性肠肽（VIP）受体拮抗剂抑制。虽然单独使用高达1微摩尔的艾塞那肽-4不会改变淀粉酶的释放，但当该肽（大于30皮摩尔）与胆囊收缩素联合使用时，观察到酶释放增强。当艾塞那肽-4与卡巴胆碱、蛙皮素或钙离子载体A23187联合使用时，也观察到淀粉酶释放增强。这些结果表明，刺激大鼠胰腺腺泡上的艾塞那肽受体可导致细胞内cAMP增加。虽然单独这种cAMP增加不会导致淀粉酶释放，但艾塞那肽-4与增加细胞内钙的药物联合使用会导致淀粉酶释放增强。
