Northfield T C, McColl I
Gut. 1973 Jul;14(7):513-8. doi: 10.1136/gut.14.7.513.
Small intestinal samples were obtained by intubation from multiple sites along the small intestine in 11 subjects with no known gastrointestinal disease eating a normal diet and at laparotomy in a further three subjects. Free (unconjugated) bile acids were consistently demonstrated in ileal samples, and occasionally in lower jejunal samples, by thin-layer chromatography, supplemented in some cases by gas/liquid chromatography and by infrared spectroscopy. The free bile acid concentration, measured enzymically following thin-layer chromatography, reached a maximum (1 mM) in the lower ileum, where it represented half the total bile acid concentration. Following ampicillin, the concentration of free bile acids decreased markedly, suggesting that they resulted from bacterial deconjugation; at the same time the total bile acid concentration increased, suggesting impaired absorption due to the reduced concentration of the more rapidly absorbed free bile acids. Our results indicate that the presence of free bile acids in lower jejunal and ileal samples is a normal finding, and cannot be taken as evidence of abnormal bacterial overgrowth. They also suggest that bacterial deconjugation at these sites may be a factor contributing to the remarkable efficiency of bile salt reabsorption.
从11名饮食正常且无已知胃肠道疾病的受试者小肠多个部位通过插管获取小肠样本，另外3名受试者则在剖腹手术时获取样本。通过薄层色谱法在回肠样本中始终检测到游离（未结合）胆汁酸，在空肠下段样本中偶尔也能检测到，某些情况下还通过气/液色谱法和红外光谱法进行补充检测。在薄层色谱法之后通过酶法测定的游离胆汁酸浓度在回肠下段达到最高值（1 mM），此时其占总胆汁酸浓度的一半。服用氨苄青霉素后，游离胆汁酸浓度显著降低，表明它们是细菌去结合作用的结果；与此同时，总胆汁酸浓度升高，这表明由于吸收较快的游离胆汁酸浓度降低导致吸收受损。我们的结果表明，空肠下段和回肠样本中存在游离胆汁酸是正常现象，不能作为细菌过度生长异常的证据。它们还表明，这些部位的细菌去结合作用可能是胆汁盐重吸收效率显著提高的一个因素。
