DETERMINANTS OF O2 EXCHANGE IN HUMAN ERYTHROCYTES

先前的研究表明，即使在湍流中，氧气的速率 人红细胞摄取部分受限于细胞外 扩散边界层(或非搅拌层)。在具体目标中， 这个项目是：(1)获取更直接的证据证明存在或 没有扩散边界层，(2)对O2进行量化 扩散边界层和红细胞膜的通透性， (3)测定红细胞物理性质对红细胞的影响 扩散边界层，(4)确定影响增强 膜胆固醇和麻醉性酒精对心肌细胞O2通透性的影响 红细胞膜，以及(5)测定乳化效果 氟碳对O2扩散边界层的渗透性。至 完成我们的目标，我们将使用标记在其上的红细胞 外表面有芘--一种O2猝灭的荧光团。监控 停流装置中的芘荧光将使我们能够 测定红细胞膜表面的氧分压 氧摄取过程。知道膜表面的氧分压和速率 对于氧气吸收，我们将计算扩散的氧气渗透率 在上述条件下的边界层和红细胞膜。 我们研究的长期目标是确定以下因素 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我们将定义限制 限定条件下停流快速反应装置的吸氧量 流动条件。当我们了解限制气体交换的因素时 通过红细胞在这个相对简单的系统中，我们将处于更好的 问是什么因素限制了体内红细胞的气体交换 供应肺泡和外周的毛细血管 纸巾。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 更好地了解体内红细胞的交换，这一知识可能 有助于为患有癌症的个人设计改进的治疗方法 由红细胞引起的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.