Ogoh Shigehiko, Brothers R Matthew, Barnes Quinton, Eubank Wendy L, Hawkins Megan N, Purkayastha Sushmita, O-Yurvati Albert, Raven Peter B
Department of Integrative Physiology, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, Texas 76107, USA.
J Appl Physiol (1985). 2006 Jan;100(1):51-9. doi: 10.1152/japplphysiol.00804.2005. Epub 2005 Sep 8.
The purpose of this study was to examine the hypothesis that the operating point of the cardiopulmonary baroreflex resets to the higher cardiac filling pressure of exercise associated with the increased cardiac filling volumes. Eight men (age 26 +/- 1 yr; height 180 +/- 3 cm; weight 86 +/- 6 kg; means +/- SE) participated in the present study. Lower body negative pressure (LBNP) was applied at 8 and 16 Torr to decrease central venous pressure (CVP) at rest and during steady-state leg cycling at 50% peak oxygen uptake (104 +/- 20 W). Subsequently, two discrete infusions of 25% human serum albumin solution were administered until CVP was increased by 1.8 +/- 0.6 and 2.4 +/- 0.4 mmHg at rest and 2.9 +/- 0.9 and 4.6 +/- 0.9 mmHg during exercise. During all protocols, heart rate, arterial blood pressure, and CVP were recorded continuously. At each stage of LBNP or albumin infusion, forearm blood flow and cardiac output were measured. During exercise, forearm vascular conductance increased from 7.5 +/- 0.5 to 8.7 +/- 0.6 U (P = 0.024) and total systemic vascular conductance from 7.2 +/- 0.2 to 13.5 +/- 0.9 l.min(-1).mmHg(-1) (P < 0.001). However, there was no significant difference in the responses of both forearm vascular conductance and total systemic vascular conductance to LBNP and the infusion of albumin between rest and exercise. These data indicate that the cardiopulmonary baroreflex had been reset during exercise to the new operating point associated with the exercise-induced change in cardiac filling volume.
心肺压力反射的工作点会重置为与运动时心脏充盈量增加相关的更高心脏充盈压力。八名男性（年龄26±1岁；身高180±3厘米；体重86±6千克；均值±标准误）参与了本研究。在休息时以及在50%峰值摄氧量（104±20瓦）的稳态腿部骑行过程中，施加8和16托的下体负压（LBNP）以降低中心静脉压（CVP）。随后，分两次分别输注25%人血清白蛋白溶液，直至休息时CVP升高1.8±0.6和2.4±0.4毫米汞柱，运动时升高2.9±0.9和4.6±0.9毫米汞柱。在所有方案实施过程中，持续记录心率、动脉血压和CVP。在LBNP或白蛋白输注的每个阶段，测量前臂血流量和心输出量。运动期间，前臂血管传导率从7.5±0.5升至8.7±0.6单位（P = 0.024），总全身血管传导率从7.2±0.2升至13.5±0.9升·分钟⁻¹·毫米汞柱⁻¹（P < 0.001）。然而，休息和运动期间，前臂血管传导率和总全身血管传导率对LBNP和白蛋白输注的反应无显著差异。这些数据表明，运动期间心肺压力反射已重置为与运动引起的心脏充盈量变化相关的新工作点。
