ADAPTATIONS TO HYPOXIA

本项目旨在研究氧气的每一种成分， 转运系统，其开始于肺的通气， 呼吸（项目A）。 在肺内，空气的分布应该是 与血液的分布相匹配，即肺部的控制 流通（项目B）。 氧气的实际传输发生在肺泡， 毛细血管灌注的控制是最重要的，并且是研究的焦点 肺微循环（Project C） 一旦充氧，血液 循环由心脏和体循环的功能决定。 最后，氧气的实际输送取决于血氧和 内容物和血液流动。 氧含量与氧气的含量直接相关 血液的承载能力，即，血红蛋白浓度和血细胞比容， 而血流量与血细胞比容（粘度）负相关。 这些 相互关系和相关因素决定全身氧输送 (new项目D）。 由于氧气运输系统必须响应 无论是氧气的供应和需求，重要的是要了解特殊的 适应高海拔的慢性缺氧（项目E）。 这些，然后， 是本计划项目中的五个主要调查领域。 的 低毒性和高碳酸血症性冲动在控制呼吸中的作用 在呼吸衰竭，睡眠和运动中，正在进行研究。 CO2大量流入肺部将作为呼吸过度的主要刺激进行检查 在运动中。 组胺，肾上腺素，血管周围肥大细胞， 缺氧的直接影响正在研究中， 控制 血管张力的变化改变了毛细血管的动力学， 血流 导致肺毛细血管募集作为一种手段的因素 将研究增强气体交换。 所有这些机制都将与 适应和适应不良的高海拔，包括怀孕，慢性 高原反应、高原肺水肿和氧气输送， 特别是在红细胞增多症的情况下。

This Program Project is structured to examine each component of the oxygen transport system which begins with ventilation of the lung under the Control of Breathing (Project A). Within the lung, the distribution of air should be matched by the distribution of blood, i.e. the Control of the Pulmonary Circulation (Project B). Actual transfer of oxygen occurs at the alveolus where control of capillary perfusion is of prime importance, and is the focus of study of the Pulmonary Microcirculation (Project C). Once oxygenated, blood circulation is determined by function of the heart and systemic circulation. Finally, the actual delivery of oxygen is dependent upon both blood oxygen content and blood flow. Oxygen content is directly related to the oxygen carrying capacity of the blood, i.e., hemoglobin concentration and hematocrit, whereas blood flow is inversely related to hematocrit (visocosity). These interrelationships and associated factors determine Systemic Oxygen Delivery (new Project D). Since the oxygen transport system must respond to changes in both oxygen supply and demand, it is of importance to understand the special adaptations to the chronic hypoxia of High Altitude (Project E). These, then, are the five major areas of investigation within this Program Project. The roles of hypotoxic and hypercapnic ventilatory drives in controlling breathing in respiratory failure, during sleep, and during exercise, are being studied. Bulk flow of CO2 to the lung will be examined as a major stimulus to hyperpnea during exercise. Histamine, prostaglandins, perivascular mast cells, and the direct effects of hypoxia are under investigation relative to pulmonary vascular control. Resulting changes in vascular tone alter the dynamics of capillary blood flow. Factors causing pulmonary capillary recruitment as a means of enhancing gas exchange will be studied. All of these mechanisms will be related to adaptation and maladaptation to High Altitude, including pregnancy, chronic mountain sickness, high altitude pulmonary edema, and oxygen transport, particularly in the presence of polycythemia.