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目的和方法： 通过ＬＡＬ 改良基质显色法和紫外光谱法观察甘氨酸／ 多粘菌素Ｂ（ＰＭＢ） 合剂体外拮抗内毒素的机制。结果：测定了各拮抗剂与内毒素中和后剩余内毒素的浓度（ 活性） ，结果表明甘氨酸／ＰＭＢ 合剂组、ＰＭＢ 组和甘氨酸组均显著低于内毒素组（ Ｐ＜ ０－０１） ，并且甘氨酸／ＰＭＢ 合剂组显著低于单独使用ＰＭＢ 组和甘氨酸组（ Ｐ＜ ０－０１） 。从紫外光谱图上可看到两种拮抗剂中和内毒素的作用是明显不同的：ＰＭＢ 可以降低内毒素的吸收峰值（２０６ ｎｍ 和２５７ｎｍ 处） ，而甘氨酸与内毒素的吸收峰值则相加（２１２ ｎｍ 和２５７ ｎｍ 处） 。结论： １） 内毒素脂质Ａ 上磷酸基团及相连的氨基葡萄糖双糖结构在甘氨酸、ＰＭＢ 作用下发生了变化，从而失去了对鲎试剂中Ｃ 因子的激活作用，并且甘氨酸、ＰＭＢ 联合应用比单独使用效果要好；２） 提示甘氨酸和ＰＭＢ 可能是分别作用在内毒素分子的不同结构部位。
OBJECTIVE AND TEST METHODS: The mechanism of antagonizing endotoxin in vitro by glycine / polymyxin B (PMB) mixture was observed by LAL modified matrix colorimetry and UV spectroscopy. Results: The concentrations (activities) of endotoxin remaining after neutralization of each antagonist and endotoxin were measured. The results showed that the concentrations of glycine / PMB mixture, PMB group and glycine group were significantly lower than those of endotoxin group (P <0-01) And the glycine / PMB mixture group was significantly lower than the PMB group and glycine group alone (P <0-01). From the ultraviolet spectrum, it can be seen that the effects of the two antagonists on endotoxin are significantly different: PMB can reduce the endotoxin absorption peak (206 nm and 257 nm), while the absorption peak of glycine and endotoxin add up (212 nm and 257 nm). Conclusions: 1) The phosphoryl group on the lipid A of endotoxin and the structure of linked glucosamine disaccharide changed under the action of glycine and PMB, which lost the activation of factor C in stilbene, and the combination of glycine and PMB Which is better than alone. 2) Suggest that glycine and PMB may act on different structural parts of endotoxin molecules respectively.