Howard M G, Collins H L, Dicarlo S E
Department of Physiology, Wayne State University, School of Medicine, Detroit, Michigan 48201-1908, USA.
Clin Exp Hypertens. 2000 May;22(4):431-44. doi: 10.1081/ceh-100100082.
We tested the hypothesis that a single bout of dynamic exercise reduces post-exercise arterial pressure, heart rate, and renal sympathetic nerve activity and attenuates the arterial baroreflex control of heart rate and renal sympathetic nerve activity in normotensive New Zealand White rabbits. Animals were chronically instrumented with right jugular venous and left femoral arterial catheters, and electrodes around the renal sympathetic nerve. Arterial pressure, heart rate, and renal sympathetic nerve activity were recorded for two hours pre-exercise and two hours after a single bout of treadmill exercise (post-exercise). Post-exercise heart rate, arterial pressure, and renal sympathetic nerve activity were elevated above pre-exercise values (71+/-3 bpm, 13+/-1 mmHg, and 80+/-21%, respectively). These data demonstrate that normotensive rabbits do not exhibit post-exercise hypotension, due in part to elevations in sympathetic nerve activity. In addition, arterial baroreflex regulation of heart rate and renal sympathetic nerve activity were determined pre- and post-exercise. Exercise shifted the baroreflex function curve for heart rate and renal sympathetic nerve activity upward and to the right without a change in gain. These data suggest that post-exercise elevations in sympathetic nerve activity are due, in part, to an elevation of the operating point of the arterial baroreflex to a higher pressure. These responses in normotensive rabbits contrast sharply with the responses in hypertensive individuals and animals. Understanding the mechanisms contributing to the differences between hypertensive and normotensive subjects may lead to measures designed to lower arterial pressure in hypertensive individuals.
单次动态运动可降低运动后动脉血压、心率和肾交感神经活动，并减弱正常血压的新西兰白兔心率和肾交感神经活动的动脉压力反射控制。动物被长期植入右颈静脉和左股动脉导管以及肾交感神经周围的电极。在运动前两小时和单次跑步机运动后两小时（运动后）记录动脉血压、心率和肾交感神经活动。运动后心率、动脉血压和肾交感神经活动高于运动前值（分别为71±3次/分钟、13±1毫米汞柱和80±21%）。这些数据表明，正常血压的兔子不会出现运动后低血压，部分原因是交感神经活动升高。此外，在运动前后测定了心率和肾交感神经活动的动脉压力反射调节。运动使心率和肾交感神经活动的压力反射功能曲线向上和向右移动，而增益不变。这些数据表明，运动后交感神经活动升高部分是由于动脉压力反射的工作点升高到更高压力。正常血压兔子的这些反应与高血压个体和动物的反应形成鲜明对比。了解导致高血压和正常血压受试者差异的机制可能会带来旨在降低高血压个体动脉血压的措施。
