Hsu B Y, McNamara P D, Mahoney S G, Fenstermacher E A, Rea C T, Bovee K C, Segal S
Division of Biochemical Development and Molecular Diseases, Children's Hospital of Philadelphia, PA 19104.
Metabolism. 1992 Mar;41(3):253-9. doi: 10.1016/0026-0495(92)90267-e.
To comprehend the renal defect underlying the idiopathic Fanconi syndrome in the Basenji dog, we have used isolated renal brush border membrane vesicles to examine two factors that influence membrane nonelectrolyte transport processes, sodium flux and membrane fluidity. We have found that there is no significant difference in the rate of uptake of 100 mmol/L 22Na+ and conclude that the previously observed defects in the sodium gradient-stimulated overshoot of glucose and of proline are not related to an alteration in the flux of sodium at physiological concentrations. Since carrier proteins exist in a lipid milieu, alteration in the physical state of the lipid membrane can determine transport function. Renal brush border preparations from normal and affected animals were studied by measuring fluorescence polarization to assess differences in the physical state of the membranes using the fluorescent probe, DPH, which quantitates inner core membrane fluidity. Membranes from affected dogs consistently showed a higher fluidity as measured by eta, a parameter of DPH fluorescence polarization. Since membrane fluidity is related to lipid composition, the data suggest that there may be an important alteration in the lipids in renal membranes of affected animals.
为了理解巴辛吉犬特发性范科尼综合征潜在的肾脏缺陷，我们使用分离的肾刷状缘膜囊泡来研究影响膜非电解质转运过程的两个因素，即钠通量和膜流动性。我们发现，100 mmol/L 22Na+ 的摄取速率没有显著差异，并得出结论，先前观察到的钠梯度刺激的葡萄糖和脯氨酸过冲缺陷与生理浓度下钠通量的改变无关。由于载体蛋白存在于脂质环境中，脂质膜物理状态的改变可以决定转运功能。使用荧光探针DPH（它可定量测量内核膜流动性）通过测量荧光偏振来评估正常和患病动物的肾刷状缘制剂，以评估膜物理状态的差异。通过DPH荧光偏振参数eta测量，患病犬的膜始终显示出更高的流动性。由于膜流动性与脂质组成有关，数据表明患病动物肾膜中的脂质可能存在重要改变。
