Said H M, Sharifian A, Bagherzadeh A, Mock D
Department of Medicine, University of California-School of Medicine, Irvine 92717.
Am J Clin Nutr. 1990 Dec;52(6):1083-6. doi: 10.1093/ajcn/52.6.1083.
This study examined the effects of chronic ethanol feeding and acute ethanol exposure in vitro on biotin transport in rat intestine. Transport studies were performed with intestinal everted sacs. Ethanol was fed to rats for 6-7 wk. Compared with pair-fed controls, ethanol feeding significantly decreased plasma biotin concentrations and transport at physiological concentrations (0.01, 0.1, and 0.3 mumol/L) but not at pharmacological concentration (100 mumol/L). When added to the incubation medium of everted jejunal sacs from dry-food-fed rats, ethanol (2% vol:vol) significantly inhibited the transport of biotin at a physiological concentration (0.1 mumol/L) but not at a pharmacological concentration (100 mumol/L). The inhibitory effect of ethanol on the transport of 0.1 mumol biotin/L increased with increasing concentration of ethanol in the incubation medium [0.5% to 5% (vol:vol)]. Acetaldehyde, the major ethanol metabolite, also significantly inhibited biotin transport at 0.2% (vol:vol). These data demonstrate that chronic ethanol feeding and acute ethanol exposure in vitro inhibit the intestinal transport of biotin by the carrier-mediated process. Chronic ethanol feeding is also associated with a significant decrease in plasma biotin concentrations. The ethanol-induced inhibition in intestinal transport of biotin may be a contributing factor in reducing plasma biotin concentrations.
本研究检测了长期乙醇喂养及体外急性乙醇暴露对大鼠肠道生物素转运的影响。采用肠外翻囊进行转运研究。乙醇喂养大鼠6 - 7周。与配对喂养的对照组相比，乙醇喂养显著降低了生理浓度（0.01、0.1和0.3μmol/L）下的血浆生物素浓度及转运，但在药理浓度（100μmol/L）下未降低。当向干粮喂养大鼠的空肠外翻囊孵育培养基中添加乙醇（2%体积比）时，乙醇在生理浓度（0.1μmol/L）下显著抑制生物素的转运，但在药理浓度（100μmol/L）下未抑制。随着孵育培养基中乙醇浓度从0.5%增至5%（体积比），乙醇对0.1μmol/L生物素转运的抑制作用增强。乙醇的主要代谢产物乙醛在浓度为0.2%（体积比）时也显著抑制生物素转运。这些数据表明，长期乙醇喂养及体外急性乙醇暴露通过载体介导的过程抑制肠道生物素转运。长期乙醇喂养还与血浆生物素浓度显著降低有关。乙醇诱导的肠道生物素转运抑制可能是血浆生物素浓度降低的一个促成因素。
