INTEGRATIVE ASPECTS OF CARDIOVASCULAR FUNCTION

描述（改编自申请人的摘要）：总体目标 本申请中提出的项目是为了进一步了解 产生血液动力学调节的机制， 锻炼的 这些研究将调查如何以及何时， 液压）因素和反射控制机制有助于这些 调整。 需要了解身体过程如何在健康中发挥作用 了解疾病。 最重要的方法是 由此循环系统的组成部分可以在一个 与调节的循环的其他元素相结合的方式。 目的一：骨骼肌的节律性收缩和舒张驱动血液 通过活动肌肉的流动，称为骨骼肌泵。 虽然 肌泵对心输出量、右心房、右心房和左心房产生深远的影响。 血压和动脉血压在运动中，相对较少， 了解肌肉泵的机械特性。 这片空白将是 通过研究孤立的肌肉泵来填充。 后肢肌 麻醉的动物将在短时间内进行自我灌注 电性收缩的症状 这将通过分流 静脉血从活动的肌肉直接流回 供应肌肉的动脉。 从本质上讲，活跃的肌肉将灌注 通过在“短路”周围驱动血液， 肌肉从其余的循环;这是类似于孤立的 心肺准备大大增加了我们对 心室泵的机械性能。 目的二：影响 心脏充盈压引起的心脏机械活动变化 将被评估。 伴随运动的心率上升， 导致血液“储存”在血液中的时间平均体积减少， 心腔，由于舒张末期时间减少 音量. 心脏容量的下降必然导致心脏收缩力的增加。 心外血容量和压力。 心脏的能力， 当心率上升时，其自身的充盈压力将通过使 心脏泵以低心率泵出相同的心输出量，然后再次以 心率很高 禁食期间心脏充盈压应更高 由于从心腔转移血液量而引起的心脏起搏 到中央静脉 目的III：静脉系统在造血中的作用 将通过确定对心脏的影响来检查心脏可用的药物。 主动改变心输出量分布的充盈压 合规和不合规发行之间的区别。 采取方法是 控制和操纵心输出量和后肢血流量（a 非顺应性循环）通过计算机控制的心室起搏， 血管封堵器袖带。 目的IV：肌肉化学感受器反射的影响， 通过使收缩的肌肉缺血或动脉压力感受器反射来刺激 刺激反应曲线将被调查，看看肌肉是否 化学感受器反射将压力感受器反射“重置”到运动中的较高操作点。 目的V：肌肉化学反射提高心脏充盈的能力 将对压力进行评估。

DESCRIPTION (Adapted from the applicant's abstract): The overall goal of the projects proposed in this application is to further our understanding of the mechanisms producing the hemodynamic adjustments that accompany dynamic exercise. The studies will investigate how, and when, mechanical (or hydraulic) factors and reflex control mechanisms contribute to these adjustments. Knowledge of how bodily processes function in health is needed to understand disease. The overriding methodological approach is one whereby the components of the circulatory system can be studied in an integrative fashion with the other elements of the circulation regulated. AIM I: Rhythmic contraction and relaxation of skeletal muscle drives blood flow through the active muscles, termed the skeletal muscle pump. Although the muscle pump exerts a profound influence on cardiac output, right atrial pressure, and arterial blood pressure in exercise, relatively little is known about the mechanical properties of the muscle pump. This void will be filled by studying the isolated muscle pump. Hindlimb muscles of anesthetized animals will be made to perfuse themselves during brief periods of electrically induced contractions. This will be accomplished by shunting venous blood draining from the active muscles directly back into the arteries supplying the muscles. In essence, the active muscles will perfuse themselves by driving blood around a "short-circuit" that isolates the muscles from the remainder of the circulation; this is analogous to isolated heart-lung preparations that have greatly increased our understanding of the mechanical properties of the ventricular pumps. AIM II: The effects of changes in the mechanical activity of the heart on cardiac filling pressure will be assessed. The rise in heart rate that accompanies exercise must lead to a decrease in the time-averaged volume of blood "stored" in the heart chambers, owing to the reduction in time spent at end-diastolic volume. A fall in heart volume must cause a reciprocal increase in extra-cardiac blood volume and pressure. The ability of the heart to raise its own filling pressure when heart rate rises will be tested by making the heart pump the same cardiac output at a low heart rate and then again at a high heart rate. Cardiac filling pressure should be higher during fast pacing of the heart owing to transfer of blood volume from cardiac chambers to central veins. AIM III: The role of the venous system in making blood available to the heart will be examined by determining the effect on cardiac filling pressure of actively changing the distribution of cardiac output between compliant and non-compliant circulations. The approach is to control and manipulate cardiac output and hindlimb blood flow (a non-compliant circulation) by computer controlled ventricular pacing and vascular occluder cuffs. AIM IV: The influence of the muscle chemoreflex, stimulated by making contracting muscles ischemic, or arterial baroreflex stimulus-response curves will be investigated to see if the muscle chemoreflex "resets" the baroreflex to a higher operating point in exercise. AIM V: The ability of the muscle chemoreflex to raise cardiac filling pressure will be assessed.