Sinar D R, Charles L G, Burns T W
Am J Physiol. 1982 Jan;242(1):G47-51. doi: 10.1152/ajpgi.1982.242.1.G47.
The myoelectric response and fluid output from in vivo rabbit ileal loops injected with B subunits of purified cholera enterotoxin are compared with the response to the purified cholera holotoxin. Migrating action-potential complex (MAPC) frequency is similar after injection of purified cholera toxin or B subunits. In contrast, fluid output after B-subunit injection is significantly (P less than 0.05) less than fluid output after purified cholera toxin injection. Specific antiserum to the holotoxin incubated with holotoxin at equivalence significantly decreased both MAPC activity (P less than 0.05) and fluid output (P less than 0.001) from the purified toxin. Purified cholera toxin and B subunits, modified by reaction with 2-nitrophenylsulfonyl chloride to produce monomeric B fractions with decreased GM1 ganglioside-binding properties, produced significantly (P less than 0.05) less fluid output and MAPC activity. Binding of the toxin or B subunits in the aggregated form is essential for the expression of MAPC activity or fluid output. These results suggest that the B subunit of cholera toxin produces MAPC activity in the rabbit ileum in the absence of fluid production. Furthermore, previous assumptions that MAPC activity is linked to fluid secretion should be reconsidered. It appears that the gut responses to cholera toxin, fluid production, or MAPC activity are produced by separate mechanisms.
将注射纯化霍乱肠毒素B亚基的体内兔回肠袢的肌电反应和液体输出与对纯化霍乱全毒素的反应进行比较。注射纯化霍乱毒素或B亚基后，移行性动作电位复合体（MAPC）频率相似。相比之下，注射B亚基后的液体输出明显（P<0.05）少于注射纯化霍乱毒素后的液体输出。与全毒素在等价条件下孵育的全毒素特异性抗血清显著降低了纯化毒素的MAPC活性（P<0.05）和液体输出（P<0.001）。通过与2-硝基苯磺酰氯反应进行修饰以产生GM1神经节苷脂结合特性降低的单体B组分的纯化霍乱毒素和B亚基，产生的液体输出和MAPC活性显著（P<0.05）降低。毒素或B亚基以聚集形式结合对于MAPC活性或液体输出的表达至关重要。这些结果表明，霍乱毒素的B亚基在不产生液体的情况下在兔回肠中产生MAPC活性。此外，应重新考虑先前关于MAPC活性与液体分泌相关的假设。看来肠道对霍乱毒素、液体产生或MAPC活性的反应是由不同机制产生的。
