PHOSPHOLIPID TRANSFER DURING INTESTINAL ABSORPTION

胆汁中混合磷脂：胆盐胶束的形成 以及它们的分泌物进入肠腔和从肠腔吸收 对胆固醇的排泄、消化和 脂肪的吸收和乳糜粒的形成。长的- 这项研究的学期目标是了解这些高度 不溶于水的磷脂在 不同的疏水环境在它们从 肝细胞转化为肠道细胞。这项提案将重点放在 关于整个过程中的三个步骤：1)在 胶束；2)从胶束转移到肠细胞刷缘 膜；以及3)跨刷状缘膜的转移。 荧光(NBD)标记的磷脂和溶血磷脂将 被用来监控每一个 以上案例。NBD荧光团的光谱性质 (量子产额对环境极性的敏感性， 高浓度自猝灭和Co++猝灭) 将用于检测NBD标记的磷脂的转移 从一个地方到另一个地方。使用这些技术，一个 配备停流快速混合装置的荧光计 检测胶束间发生的快速磷脂转移 和膜，以及跨膜。动力学建模将是 用于确定每一种机制所涉及的机制 上述过程中的一部分。

The formation of mixed phospholipid: bile salt micelles in the bile and their secretion into and absorption from the intestinal lumen are essential to the excretion of cholesterol, the digestion and absorption of fats, and the formation of chylomicrons. The long- term objective of this research is to understand how these highly water-insoluble phospholipids are rapidly transferred between the different hydrophobic environments during their movement from liver hepatocytes to intestinal enterocytes. This proposal focuses on three steps in the overall process: 1) transfer between micelles; 2) transfer from micelles to the enterocyte brush-border membrane; and 3) transfer across the brush-border membrane. Fluorescent (NBD)-labeled phospholipids and lysophospholipids will be used to monitor the rapid transfer involved in each of the above cases. The spectral properties of the NBD fluorophore (sensitivity of quantum yield to the polarity of the environment, self-quenching at high concentrations, and quenching by Co++) will be used to detect the transfer of NBD-labeled phospholipids from one location to another. Using these techniques, a fluorometer equipped with a stopped-flow rapid mixing device can detect the fast phospholipid transfer that occurs between micelles and membranes, and across membranes. Kinetic modeling will be used to determine the mechanism or mechanisms involved in each of the above processes.