Journal of Applied Physiology, Vol 74, Issue 6 2672-2680, Copyright © 1993 by American Physiological Society

ARTICLES

Importance of left atrial baroreceptors in the cardiopulmonary baroreflex of normal humans

R. M. Oren, H. P. Schobel, R. M. Weiss, W. Stanford and D. W. Ferguson
Department of Internal Medicine, University of Iowa Hospitals and Clinics, Iowa City 52242.

In animals, sympathetic responses to orthostasis are regulated in part by cardiopulmonary afferents arising from atrial and ventricular baroreceptors. To determine the relative importance of these baroreceptor regions in the cardiopulmonary baroreflex of normal humans, simultaneous measurements of left atrial and right and left ventricular volumes (cine computed tomography), invasive hemodynamics, forearm vascular resistance (plethysmography), and efferent sympathetic nerve activity to muscle (microneurography) were obtained under control conditions and with nonhypotensive lower body negative pressure (-10 mmHg, LBNP-10) in nine normal human subjects. LBNP-10 did not alter heart rate or mean systemic arterial pressure, but it did produce significant decreases in pulmonary artery diastolic and right atrial pressures. This reduction in cardiac filling pressures resulted in efferent sympathoexcitation evidenced by increases in forearm vascular resistance and efferent sympathetic nerve activity to the muscle. LBNP-10 did not alter end-diastolic volume of the left or the right ventricle. Similarly, ventricular stroke volume was unchanged during LBNP-10, as assessed by cine computed tomography or thermodilution techniques. In contrast, LBNP-10 resulted in a significant decrease in left atrial volume. Thus, LBNP produced a significant decrease in cardiac filling pressures and left atrial volumes with resultant reflex sympathoexcitation, whereas ventricular volumes were unchanged. These observations suggest an important role for left atrial (nonventricular) baroreceptor afferents in the cardiopulmonary baroreflex of normal humans.

This article has been cited by other articles:

				F. C. de Carvalho, F. M. Consolim-Colombo, C. A. Pastore, M. C. Rubira, J. C. Meneguetti, E. M. Krieger, and M. Wajngarten Acute reduction of ventricular volume decreases QT interval dispersion in elderly subjects with and without heart failure Am J Physiol Heart Circ Physiol, May 1, 2005; 288(5): H2171 - H2176. [Abstract] [Full Text] [PDF]

				H. P. Schobel, H. Frank, R. Naraghi, H. Geiger, E. Titz, and K. Heusser Hypertension in Patients with Neurovascular Compression Is Associated with Increased Central Sympathetic Outflow J. Am. Soc. Nephrol., January 1, 2002; 13(1): 35 - 41. [Abstract] [Full Text] [PDF]

				J. S. Floras, G. C. Butler, S.-I. Ando, S. C. Brooks, M. J. Pollard, and P. Picton Differential sympathetic nerve and heart rate spectral effects of nonhypotensive lower body negative pressure Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2001; 281(2): R468 - R475. [Abstract] [Full Text] [PDF]

				D Johnson, H Perrault, S J Vobecky, F Trudeau, E Delvin, A Fournier, and A Davignon Resetting of the cardiopulmonary baroreflex 10 years after surgical repair of coarctation of the aorta Heart, March 1, 2001; 85(3): 318 - 325. [Abstract] [Full Text]

				F. M. Consolim-Colombo, J. A. B. Filho, H. F. Lopes, C. R. R. Sobrinho, M. E. Otto, G. M. G. Riccio, C. Mady, and E. M. Krieger Decreased Cardiopulmonary Baroreflex Sensitivity in Chagas' Heart Disease Hypertension, December 1, 2000; 36(6): 1035 - 1039. [Abstract] [Full Text] [PDF]

				E. R. Azevedo, G. E. Newton, J. S. Floras, and J. D. Parker Reducing Cardiac Filling Pressure Lowers Norepinephrine Spillover in Patients With Chronic Heart Failure Circulation, May 2, 2000; 101(17): 2053 - 2059. [Abstract] [Full Text] [PDF]

				A. J. Minisi Vagal Cardiopulmonary Reflexes After Total Cardiac Deafferentation Circulation, December 8, 1998; 98(23): 2615 - 2620. [Abstract] [Full Text] [PDF]

				B. Pump, N. J. Christensen, R. Videbak, J. Warberg, O. Hendriksen, and P. Norsk Left atrial distension and antiorthostatic decrease in arterial pressure and heart rate in humans Am J Physiol Heart Circ Physiol, December 1, 1997; 273(6): H2632 - H2638. [Abstract] [Full Text] [PDF]