Dynamic cardiovascular, respiratory, cerebrovascular interactions

我们适应日常生活挑战的能力取决于骨骼肌和大脑的血流量供应。我们计划探索两个主题，突出氧气输送到工作肌肉的重要作用，并开发明确测量脑血流量的方法。我们的第一个实验将探讨缺血预处理对增强肌肉功能的影响。缺血预处理是通过在更大的血流挑战之前短时间限制血流来完成的。最近我们的研究表明，在运动前停止肌肉的血液流动，然后允许短暂的恢复，会延迟肌肉代谢的适应。我们预计，缺血预处理将使肌肉为更长时间的血流停滞做好准备，使肌肉能够很好地应对运动。我们将在现有的技术基础上增加磁共振波谱来监测肌肉内代谢事件。通过改变吸入气体浓度来控制对肌肉的氧气供应，将使我们能够验证在体育活动开始时氧气在调节肌肉代谢中的重要性的假设。我们的第二个系列实验将检查在几种情况下流向大脑的血液。我们将比较通过大脑中动脉的脑血流速度和颈部颈内动脉的绝对血流。在初步研究中，我们确定在许多情况下，大脑中动脉流速的估计是不正确的。我们将研究不同药物对脑血管的影响，血液中二氧化碳含量的变化和姿势的变化，以表明速度并不能准确反映脑血流量。我们将探索脑血管特性的新模型如何使我们深入了解脑血流精确调节的机制。通过这项研究，学生将获得关于心血管和脑血流综合机制的重要知识，这些机制有助于我们日常生活中身体活动和直立姿势的人体生理反应。

Our ability to adapt to the challenges of daily life depends on blood flow supply to the working skeletal muscles and to the brain. We plan to explore two topics that highlight the important role of oxygen delivery to working muscles and develop methods that explicitly measure brain blood flow. Our first experiments will explore the impact of ischemic preconditioning to enhance muscle function. Ischemic preconditioning is accomplished by restricting blood flow for short periods of time before a larger challenge to blood flow. Recently we showed that stopping blood flow to a muscle then allowing a brief recovery prior to exercise delayed adaptation of muscle metabolism. We anticipate that ischemic preconditioning will prepare the muscle for the challenge of longer arrest of blood flow allowing the muscle to cope well with exercise. We will add magnetic resonance spectroscopy to our existing techniques to monitor intramuscular metabolic events. Manipulation of oxygen supply to the muscle by changing inspired gas concentrations will allow us to test hypotheses showing the importance of oxygen in regulation of muscle metabolism at the onset of physical activity. Our second series of experiments will examine blood flow to the brain under several conditions. We will compare estimates from brain blood flow velocity through the middle cerebral artery to absolute blood flow in the internal carotid artery in the neck. In preliminary research, we determined that the estimates from the middle cerebral artery velocity are incorrect in many circumstances. We will investigate the effects of different drugs that affect brain blood vessels, changes in blood levels of carbon dioxide and changes in posture to show that velocity does not accurately reflect brain blood flow. We will explore how new models of the properties of brain blood vessels can give us insight into the mechanisms that underlie the precise regulation of brain blood flow. Through this research, students will gain critical knowledge about the integrative cardiovascular and brain blood flow mechanisms that contribute to human physiological responses to physical activity and upright posture in our everyday lives.