ABSTRACT

1. Myo-inositol (MI) is an essential metabolite for cell function in animals and humans. The aim of this study was to characterise the transport mechanism of MI in the small intestine of laying hens as there is a lack of knowledge about the MI uptake mechanisms. The hypothesised secondary active, cation coupled transport of MI was assessed by electrophysiological measurements with Ussing chambers, and was compared to the electrophysiology of glucose transport.

2. Twenty-six laying hens were used. The potential ion-dependent transport was tested in tissue of the small intestine. Barrier function of the tissue was shown by determining the transepithelial resistance. During the experiments, mucosal and serosal buffers were sampled to measure time-dependent changes in MI concentrations. Samples from eight hens were further used for Western blot analyses of the jejunal apical membranes.

3. Active MI transport, indicated by changes in the short circuit current after MI addition, could not be demonstrated in the Ussing chambers experiments. MI was further not detectable in the serosal buffer, nor in the lysates of mucosal tissue cytoplasm nor lipids. Thus, there was no evidence for a MI transport or absorption. However, Western blot analyses of the jejunal apical membrane revealed signals indicated the expression of the MI transport proteins SMIT-1 and SMIT-2.

4. In conclusion, the MI transport process in the chicken intestine is more complex than it was presumed and is probably influenced by still unknown regulations or metabolic processes.

摘要

1.肌醇(MI) 是动物和人类细胞功能的必需代谢物。本研究的目的是描述 MI 在蛋鸡小肠中的转运机制，因为缺乏关于 MI 摄取机制的知识。通过使用 Ussing 室的电生理测量来评估 MI 的假设的二级活性阳离子耦合转运，并与葡萄糖转运的电生理学进行比较。

2. 使用了 26 只蛋鸡。在小肠组织中测试了潜在的离子依赖性转运。通过确定跨上皮阻力显示组织的屏障功能。在实验过程中，对粘膜和浆膜缓冲液进行取样以测量 MI 浓度的时间依赖性变化。八只母鸡的样品进一步用于空肠顶膜的蛋白质印迹分析。

3. 主动 MI 传输，由添加 MI 后短路电流的变化表示，在 Ussing 室实验中无法证明。在浆膜缓冲液、粘膜组织细胞质的裂解物和脂质中也检测不到 MI。因此，没有证据表明 MI 转运或吸收。然而，空肠顶膜的蛋白质印迹分析显示信号表明 MI 转运蛋白 SMIT-1 和 SMIT-2 的表达。

4. 总之，鸡肠中的 MI 转运过程比假设的要复杂，并且可能受到仍然未知的法规或代谢过程的影响。