Smith D D, Li J, Wang Q, Murphy R F, Adrian T E, Elias Y, Bockman C S, Abel P W
Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska 68178.
J Med Chem. 1993 Aug 20;36(17):2536-41. doi: 10.1021/jm00069a012.
C-terminally truncated fragments of human alpha-calcitonin gene-related peptide (h-alpha-CGRP) were tested for their ability to stimulate amylase secretion from pancreatic acinar cells and relax precontracted mesenteric arteries. h-alpha-CGRP, h-alpha-CGRP (1-36), h-alpha-CGRP (1-35), and h-alpha-CGRP (1-34) were made by Merrifield's solid-phase peptide synthesis methodology. Peptides were purified by gel filtration, cation-exchange chromatography, and semipreparative reversed-phase high-performance liquid chromatography. The products were characterized by amino acid analysis, mass spectrometry, and tryptic digestion. h-alpha-CGRP stimulated amylase secretion from dispersed guinea pig pancreatic acini in a biphasic concentration-dependent manner. The initial increase in amylase secretion reached 8% of total cellular amylase content with an ED50 value of 7.7 nM, and the second increase reached 11% of total cellular amylase content at a concentration of h-alpha-CGRP of 10(-4)M. h-alpha-CGRP (1-36) caused a small, significant increase in amylase release. C-terminally truncated fragments h-alpha-CGRP (1-35) and h-alpha-CGRP (1-34) did not increase amylase release at concentrations < 10(-5) M. At concentrations > 10(-5) M the fragments h-alpha-CGRP (1-35) and h-alpha-CGRP (1-34) caused a smaller increase in amylase release than that caused by h-alpha-CGRP whereas h-alpha-CGRP (1-36) caused the same increase. h-alpha-CGRP caused a concentration-dependent relaxation of rat mesenteric artery, precontracted with prostaglandin F2 alpha, with an EC50 of 2.9 nM and a maximal relaxation that was 60% of the prostaglandin F2 alpha-induced tone. h-alpha-CGRP (1-35) also relaxed the mesenteric artery in a concentration-dependent manner with a maximum response that was 40% of the prostaglandin F2 alpha-induced tone. The remaining fragments did not relax rat mesenteric arteries. Additionally, h-alpha-CGRP (1-36) and h-alpha-CGRP (1-34) did not block h-alpha-CGRP-induced relaxation of the mesenteric artery. An intact C-terminus is required for h-alpha-CGRP to cause potent biological effects in pancreatic acini and mesenteric artery. The different effects of h-alpha-CGRP (1-35) in mesenteric artery compared with those in pancreatic acini suggest that the CGRP receptors in these two tissues may be different.
对人α-降钙素基因相关肽（h-α-CGRP）的C末端截短片段进行了测试，以考察它们刺激胰腺腺泡细胞分泌淀粉酶以及舒张预收缩肠系膜动脉的能力。h-α-CGRP、h-α-CGRP（1-36）、h-α-CGRP（1-35）和h-α-CGRP（1-34）采用梅里菲尔德固相肽合成方法制备。通过凝胶过滤、阳离子交换色谱和半制备反相高效液相色谱对肽进行纯化。通过氨基酸分析、质谱和胰蛋白酶消化对产物进行表征。h-α-CGRP以双相浓度依赖性方式刺激分散的豚鼠胰腺腺泡分泌淀粉酶。淀粉酶分泌的初始增加量达到细胞总淀粉酶含量的8%，ED50值为7.7 nM，第二次增加在h-α-CGRP浓度为10⁻⁴M时达到细胞总淀粉酶含量的11%。h-α-CGRP（1-36）使淀粉酶释放量有小幅但显著的增加。C末端截短片段h-α-CGRP（1-35）和h-α-CGRP（1-34）在浓度<10⁻⁵M时不会增加淀粉酶释放。在浓度>10⁻⁵M时，h-α-CGRP（1-35）和h-α-CGRP（1-34）片段引起的淀粉酶释放增加量小于h-α-CGRP引起的增加量，而h-α-CGRP（1-36）引起的增加量相同。h-α-CGRP使经前列腺素F2α预收缩的大鼠肠系膜动脉发生浓度依赖性舒张，EC50为2.9 nM，最大舒张程度为前列腺素F2α诱导张力的60%。h-α-CGRP（1-35）也以浓度依赖性方式舒张肠系膜动脉，最大反应为前列腺素F2α诱导张力的40%。其余片段不会舒张大鼠肠系膜动脉。此外，h-α-CGRP（1-36）和h-α-CGRP（1-34）不会阻断h-α-CGRP诱导的肠系膜动脉舒张。h-α-CGRP在胰腺腺泡和肠系膜动脉中产生有效生物学效应需要完整的C末端。h-α-CGRP（1-35）在肠系膜动脉和胰腺腺泡中的不同效应表明这两种组织中的CGRP受体可能不同。
