Effects of changes in central blood volume on carotid-vasomotor baroreflex sensitivity at rest and during exercise

• Published in: Journal of applied physiology (1985) Vol. 101; no. 1; pp. 68 - 75
• Main Authors: Ogoh, Shigehiko, Brothers, R. Matthew, Barnes, Quinton, Eubank, Wendy L, Hawkins, Megan N, Purkayastha, Sushmita, O-Yurvati, Albert, Raven, Peter B
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.07.2006; American Physiological Society
• Subjects: Adult; Baroreflex - physiology; Biological and medical sciences; Blood pressure; Blood Pressure - physiology; Blood Volume - drug effects; Blood Volume - physiology; Cardiology; Carotid Arteries - innervation; Carotid Arteries - physiology; Comparative studies; Exercise; Exercise - physiology; Factor VIII - physiology; Fundamental and applied biological sciences. Psychology; Heart Rate - physiology; Humans; Hypovolemia - physiopathology; Lower Body Negative Pressure; Male; Pressoreceptors - physiology; Rest - physiology; Sensitivity analysis; Serum Albumin - pharmacology; Studies; Vasomotor System - physiology; Physical exercise; Central venous pressure; Cardiopulmonary; Artery; Arterial blood; Vertebrata; Rest; Sensitivity; Mammalia; arterial blood pressure; Blood volume; Blood vessel; Baroreflex; Carotid; cardiopulmonary baroreceptors; Arterial pressure; Blood pressure; Circulatory system; Hemodynamics; Baroreceptor
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.01452.2005

Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth, Texas Submitted 16 November 2005 ; accepted in final form 21 March 2006 The purpose of this investigation was to examine whether the effect of changes in central blood volume on carotid-vasomotor baroreflex sensitivity at rest was the same during exercise. Eight men (means ± SE: age 26 ± 1 yr; height 180 ± 3 cm; weight 86 ± 6 kg) participated in the present study. Sixteen Torr of lower body negative pressure (LBNP) were applied to decrease central venous pressure (CVP) at rest and during steady-state leg cycling at 50% peak O 2 uptake (104 ± 20 W). Subsequently, infusions of 25% human serum albumin solution were administered to increase CVP at rest and during exercise. During all protocols, heart rate, arterial blood pressure, and CVP were recorded continuously. At each stage of LBNP or albumin infusion, the maximal gain (G max ) of the carotid-vasomotor baroreflex function curve was measured using the neck pressure and neck suction technique. LBNP reduced CVP and increased the G max of the carotid-vasomotor baroreflex function curve at rest (+63 ± 25%, P = 0.006) and during exercise (+69 ± 19%, P = 0.002). In contrast to the LBNP, increases in CVP resulted in the G max of the carotid-vasomotor baroreflex function curve being decreased at rest –8 ± 4% and during exercise –18 ± 5% ( P > 0.05). These findings indicate that the relationship between CVP and carotid-vasomotor baroreflex sensitivity was nonlinear at rest and during exercise and suggests a saturation load of the cardiopulmonary baroreceptors at which carotid-vasomotor baroreflex sensitivity remains unchanged. cardiopulmonary baroreceptors; arterial blood pressure; central venous pressure Address for reprint requests and other correspondence: S. Ogoh, Dept. of Integrative Physiology, Univ. of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107 (e-mail: sogoh{at}hsc.unt.edu )