Al-Balool Fawzia Y
Department of Biological Sciences, Faculty of Science, Kuwait University, P.O. Box 5969, Safat 13060, State of Kuwait.
Comp Biochem Physiol C Toxicol Pharmacol. 2005 May;141(1):1-7. doi: 10.1016/j.cca.2005.02.004.
The effects of mucosally added Escherichia coli heat stable enterotoxin (STa, 30 ng mL(-1)) on the basal short-circuit current (Isc in microA cm(-2)) across stripped and unstripped sheets of proximal, mid and distal colon were investigated. Samples were taken from fed, starved (4 days, water ad lib) and undernourished (50% of control food intake for 21 days) gerbils (Gerbillus cheesmani). The effect of neurotoxin tetrodotoxin (TTX 10 microM) and the effect of replacing chloride by gluconate or the effect of removing bicarbonate from bathing buffer on the maximum increase in Isc induced by E. coli heat stable enterotoxin STa were also investigated. The results showed that there is a segmental difference both in the basal and STa-induced Isc. Also, STa is more effective in the proximal than distal colon in the three feeding conditions. Undernourishment raised the STa-induced Isc in the three regions of the colon. In fed and starved gerbils part of STa-induced Isc in the proximal colon was chloride-dependent, while the other was bicarbonate-dependent; in the mid colon, the STa-induced Isc was bicarbonate-dependent only. In the three regions of the colon taken from undernourished gerbil, the STa-induced Isc was both chloride-and bicarbonate-dependent. The increase in STa-induced Isc as a results of undernourishment in proximal and mid colon was chloride-dependent, while in the distal colon, it was both chloride- and bicarbonate-dependent.
研究了经黏膜添加大肠杆菌热稳定肠毒素（STa，30 ng mL⁻¹）对近端、中段和远端结肠剥离及未剥离肠段基础短路电流（Isc，单位为μA cm⁻²）的影响。样本取自喂食、饥饿（4天，自由饮水）和营养不良（21天摄入对照食物量的50%）的沙鼠（Gerbillus cheesmani）。还研究了神经毒素河豚毒素（TTX 10 μM）的作用，以及用葡萄糖酸盐替代氯离子或从浴液缓冲液中去除碳酸氢盐对大肠杆菌热稳定肠毒素STa诱导的Isc最大增加量的影响。结果表明，基础Isc和STa诱导的Isc均存在节段差异。此外，在三种喂养条件下，STa在近端结肠比远端结肠更有效。营养不良使结肠三个区域STa诱导的Isc升高。在喂食和饥饿的沙鼠中，近端结肠部分STa诱导的Isc依赖于氯离子，而另一部分依赖于碳酸氢盐；在中段结肠，STa诱导的Isc仅依赖于碳酸氢盐。在取自营养不良沙鼠的结肠三个区域中，STa诱导的Isc既依赖于氯离子也依赖于碳酸氢盐。近端和中段结肠因营养不良导致的STa诱导的Isc增加依赖于氯离子，而在远端结肠，它既依赖于氯离子也依赖于碳酸氢盐。
