O'Flaherty L, Stapleton P P, Redmond H P, Bouchier-Hayes D
Royal College of Surgeons in Ireland, Department of Surgery, Beaumont Hospital, Dublin, Ireland.
J Surg Res. 1997 May;69(2):331-6. doi: 10.1006/jsre.1997.5067.
Intracellular enterocytic levels of the immunomodulator taurine decrease significantly in response to trauma and surgical insult. The effect of physiological stress on enterocyte taurine uptake is unknown. The aim of this study was to compare taurine transport under basal and stressed conditions using the human intestinal Caco-2 cell line in vitro. Caco-2 cells were incubated with 10 nM [1,2-3H]taurine at 37 degrees C and 5% CO2 and taurine uptake was examined over the range of 0.1-10 microM to determine kinetic parameters of the transporter. The culture medium was then supplemented with dexamethasone and/or lipopolysaccharide (LPS) and taurine uptake was calculated as picomoles per milligram protein per hour. Statistics were by unpaired Student's t test. Taurine uptake was hyperbolically related to taurine concentration and obeyed Michaelis-Menten kinetics with a K(m) of 5.27 +/- 0.95 microM and Vmax of 1125.43 +/- 130.9 pmole/mg protein/ hour. Dexamethasone (1-1000 microM) significantly reduced taurine uptake by up to 66.15%. LPS (1 microgram/ml) impaired transport of taurine by 15.7%, and in combination with dexamethasone (100 microM) by 42.4%. All results are mean of at least three experiments and P < 0.05. We have established that taurine uptake by enterocytes is downregulated by dexamethasone. This may relate to the decreased intestinal levels of taurine observed in trauma and surgery patients. Further study may elucidate mechanisms whereby homeostasis of enterocyte taurine might be maintained during sepsis.
免疫调节剂牛磺酸的细胞内肠细胞水平会因创伤和手术损伤而显著降低。生理应激对肠细胞牛磺酸摄取的影响尚不清楚。本研究的目的是使用人肠道Caco-2细胞系在体外比较基础条件和应激条件下的牛磺酸转运。将Caco-2细胞在37℃和5%二氧化碳条件下与10 nM [1,2-³H]牛磺酸孵育，并在0.1 - 10 μM范围内检测牛磺酸摄取，以确定转运体的动力学参数。然后在培养基中添加地塞米松和/或脂多糖（LPS），并将牛磺酸摄取量计算为每毫克蛋白质每小时的皮摩尔数。采用非配对学生t检验进行统计学分析。牛磺酸摄取与牛磺酸浓度呈双曲线关系，符合米氏动力学，K(m)为5.27 ± 0.95 μM，Vmax为1125.43 ± 130.9 pmole/mg蛋白质/小时。地塞米松（1 - 1000 μM）可使牛磺酸摄取显著降低达66.15%。LPS（1 μg/ml）使牛磺酸转运受损15.7%，与地塞米松（100 μM）联合使用时受损42.4%。所有结果均为至少三次实验的平均值，P < 0.05。我们已经确定，地塞米松可下调肠细胞对牛磺酸的摄取。这可能与创伤和手术患者肠道中牛磺酸水平降低有关。进一步的研究可能会阐明在脓毒症期间维持肠细胞牛磺酸稳态的机制。
