DETERMINANTS OF O2 EXCHANGE IN HUMAN ERYTHROCYTES

先前的研究表明，即使在湍流中， 人红细胞的摄取部分受到细胞外 扩散边界层（或无搅拌层）。 在具体目标中， （1）获取更直接的证据， 不存在扩散边界层，（2）量化O2 扩散边界层和红细胞质膜的渗透性， (3)为了确定红细胞的物理性质对 扩散边界层，（4）确定增加的影响 膜胆固醇和麻醉醇对O2渗透性的影响 红细胞膜，和（5）以确定乳化的影响， 碳氟化合物对扩散边界层的O2渗透性的影响。 到 为了实现我们的目标，我们将使用标记在其 外表面有芘--一种O2猝灭的荧光团。 监测 停流装置中的芘荧光将允许我们 测定红细胞膜表面的PO 2 O2吸收过程。 了解膜表面的PO 2和 的O2吸收，我们将计算扩散的O2渗透率 边界层和红细胞膜在上述条件下。 我们研究的长期目标是确定 限制体内人红细胞的气体交换速率。 在 在本提案中描述的研究中，我们将定义限制 停流快速反应装置中的O2吸收 流动的条件。 当我们了解了限制气体交换的因素 在这个相对简单的系统中，我们将在一个更好的 在体内红细胞气体交换的限制因素是什么？ 毛细血管供应肺泡和外周 组织中 我们的工作涉及的科学学科有：生理学， 生物物理学和生物化学。 当限制气体速率的因素 更好地理解体内红细胞的交换，这一知识可以 有助于为患有以下疾病的个体设计改进的疗法： 涉及红细胞气体交换受损的疾病。

Previous research suggests that even in turbulent flow the rate of O2 uptake by human erythrocytes is partly limited by an extracellular diffusion boundary layer (or unstirred layer). Among the specific aims of this project are: (1) to obtain more direct evidence for the presence or absence of the diffusion boundary layer, (2) to quantify the O2 permeabilities of diffusion boundary layer and erythrocyte plasma membrane, (3) to determine the influence of physical properties of the red cell on diffusion boundary layer, (4) to determine the influence of increased membrane cholesterol and anesthetic alcohols on the O2 permeability of the red cell membrane, and (5) to determine the effects of emulsified fluorocarbon on the O2 permeability of the diffusion boundary layer. To accomplish our objectives we will use erythrocytes labeled at their external surfaces with pyrene -- an O2-quenched fluorophore. Monitoring the pyrene fluorescence in a stopped-flow apparatus will allow us to determine the PO2 at the erythrocyte membrane surface during the time course of O2 uptake. Knowing the PO2 at the membrane surface and the rate of O2 uptake, we will calculate the O2 permeabilities of the diffusion boundary layer and the red cell membrane under the conditions mentioned. The long-term objectives of our research are to define the factors that limit the rate of gas exchange by human erythrocytes in vivo. In the research described in this proposal we will define the factors that limit O2 uptake in a stopped-flow rapid reaction apparatus under defined conditions of flow. When we understand the factors that limit gas exchange by erythrocytes in this relatively simple system, we will be in a better position to ask what factors limit gas exchange by erythrocytes in vivo in the capillaries that supply the pulmonary alveoli and the peripheral tissues. The scientific disciplines involved in our work are: physiology, biophysics, and biochemistry. When the factors that limit the rate of gas exchange by erythrocytes in vivo are better understood, this knowledge may be useful in devising improved therapies for individuals who suffer from diseases that involve impaired gas exchange by erythrocytes.