Schorderet M, Hof P, Magistretti P J
Peptides. 1984 Mar-Apr;5(2):295-8. doi: 10.1016/0196-9781(84)90222-5.
The effects of VIP and related-peptides (PHI, secretin, glucagon) on cyclic AMP formation were investigated in intact pieces of rabbit retina. VIP and PHI increased cyclic AMP levels with EC50 of 160 nM and 300 nM respectively. At 5 microM the peptides increased cyclic AMP 46 fold (VIP) and 38 fold (PHI). Secretin was much less potent and glucagon was totally inactive. VIP was also tested for its effects on glycogen levels under similar experimental conditions. In contrast to its pronounced glycogenolytic action in mouse cerebral cortical slices, VIP at 1 microM decreased only moderately (38.3%) 3H-glycogen newly synthesized from 3H-glucose by pieces of rabbit retina. Furthermore a discrepancy between the efficacy of VIP in increasing cyclic AMP and in promoting glycogenolysis appears to exist. A similar dissociation between these two cellular events was also observed with other neuroactive substances. Thus the pronounced increase in cyclic AMP induced by dopamine and forskolin was accompanied by only a moderate decrease in 3H-glycogen levels. Conversely 50 mM potassium induced a 79.9% decrease in 3H-glycogen levels without any significant increase in cyclic AMP.
在兔视网膜完整组织块中研究了血管活性肠肽（VIP）及相关肽（PHI、促胰液素、胰高血糖素）对环磷酸腺苷（cAMP）生成的影响。VIP和PHI可提高cAMP水平，其半数有效浓度（EC50）分别为160 nM和300 nM。在5 μM时，这些肽使cAMP增加46倍（VIP）和38倍（PHI）。促胰液素的作用效力低得多，胰高血糖素则完全无活性。在类似实验条件下还检测了VIP对糖原水平的影响。与它在小鼠大脑皮质切片中明显的糖原分解作用相反，1 μM的VIP仅使兔视网膜组织块新合成的3H-糖原从3H-葡萄糖中适度减少（38.3%）。此外，VIP在提高cAMP和促进糖原分解方面的效力似乎存在差异。在其他神经活性物质作用下也观察到这两种细胞事件之间存在类似的分离现象。因此，多巴胺和福斯高林引起的cAMP显著增加仅伴随着3H-糖原水平适度下降。相反，50 mM钾使3H-糖原水平下降79.9%，而cAMP无任何显著增加。
