Csáky T Z, Ho P M
J Gen Physiol. 1966 Sep;50(1):113-28. doi: 10.1085/jgp.50.1.113.
The rate of absorption of glucose, galactose, and 3-0-methylglucose was studied in the rat's small intestine perfused in situ with isosmotic solutions containing these sugars and Na(2)SO(4) or K2SO(4). The presence of high [K(+)] in the lumen enhances absorption of glucose but not that of galactose or of 3-0-methylglucose. The potassium stimulation is apparent at higher glucose concentrations where primarily carrier-mediated diffusion is involved in the translocation. In this case potassium stimulates transport even if it is the only cation in the lumen. The potassium-stimulated intestine produces more glycogen with higher specific activity than the control gut. Lactic acid production by the intestine is markedly enhanced if the intestinal lumen is perfused with a solution containing glucose and high [K(+)]. It is concluded that potassium does not affect permeability or the specific sugar transport system of the gut, but enhances intracellular metabolic disappearance of glucose thereby creating a larger luminal intracellular concentration gradient which in turn enhances the rate of carrier-facilitated entry.
在大鼠原位灌注含葡萄糖、半乳糖和 3 - O - 甲基葡萄糖以及硫酸钠或硫酸钾的等渗溶液的小肠中，研究了这些糖类的吸收速率。肠腔内高浓度的[K⁺]可增强葡萄糖的吸收，但对半乳糖或 3 - O - 甲基葡萄糖的吸收无影响。钾离子的刺激作用在较高葡萄糖浓度时明显，此时主要是载体介导的扩散参与转运。在这种情况下，即使钾离子是肠腔内唯一的阳离子，它也能刺激转运。与对照肠道相比，受钾离子刺激的肠道产生的糖原具有更高的比活性。如果用含葡萄糖和高浓度[K⁺]的溶液灌注肠腔，肠道乳酸生成会显著增强。得出的结论是，钾离子不影响肠道的通透性或特定糖类转运系统，但会增强葡萄糖在细胞内的代谢消失，从而形成更大的肠腔 - 细胞内浓度梯度，进而提高载体介导的进入速率。
