Lind C D, Guerrant R L, Kurosky A, Mathias J R
Department of Internal Medicine, University of Virginia, Charlottesville.
J Pharmacol Exp Ther. 1991 Aug;258(2):647-51.
The migrating action potential complex (MAPC), a single ring contraction that propels luminal contents abroad, is elicited by Vibrio cholerae and its enterotoxin, choleragen (A1A2B5), in rabbit ileal loops in vivo. Choleragenoid (B5; the binding subunit) was shown previously to induce MAPCs without activating the adenylate cyclase system and without stimulating fluid output. We restudied purified B5 (extracted by high-performance liquid chromatography) to assess its effects on the myoelectric activity of rabbit ileum: can MAPC activity can be induced without associated fluid production? Four different B5 preparations and two controls, V. cholerae and sterile saline, were used. MAPC activity and ileal fluid output were significantly increased in animals inoculated with A1A2B5 (V. cholerae-El Tor) compared with all other preparations and controls. Importantly, MAPC activity and fluid output in all B5 groups did not differ from those in saline controls, demonstrating that purified B5 does not induce MAPC activity in rabbit ilium in vivo. The previous study showing B5-induced MAPCs may have resulted from A1A2B5 contamination. These results suggest A1A2B5-induced adenylate cyclase activation; myoelectric activity may be interrelated with holotoxin binding that causes a neural response.
迁移性动作电位复合体（MAPC）是一种推动肠腔内容物向前移动的单环收缩，在体内兔回肠袢中由霍乱弧菌及其肠毒素霍乱原（A1A2B5）引发。先前已表明霍乱类毒素（B5；结合亚基）可诱导MAPC，而不激活腺苷酸环化酶系统，也不刺激液体分泌。我们重新研究了纯化的B5（通过高效液相色谱法提取），以评估其对兔回肠肌电活动的影响：能否在不产生相关液体的情况下诱导MAPC活性？使用了四种不同的B5制剂以及两种对照物，即霍乱弧菌和无菌盐水。与所有其他制剂和对照物相比，接种A1A2B5（霍乱弧菌 - 埃尔托生物型）的动物的MAPC活性和回肠液体分泌显著增加。重要的是，所有B5组的MAPC活性和液体分泌与盐水对照组并无差异，这表明纯化的B5在体内兔回肠中不会诱导MAPC活性。先前显示B5诱导MAPC的研究可能是由A1A2B5污染导致的。这些结果表明A1A2B5诱导腺苷酸环化酶激活；肌电活动可能与引起神经反应的全毒素结合相关。
