Journal of Applied Physiology, Vol 69, Issue 3 962-967, Copyright © 1990 by American Physiological Society

ARTICLES

Comparison of phenylephrine bolus and infusion methods in baroreflex measurements

J. T. Sullebarger, C. S. Liang, P. D. Woolf, A. E. Willick and J. F. Richeson
Department of Medicine, University of Rochester Medical Center, New York 14642.

Phenylephrine (PE) bolus and infusion methods have both been used to measure baroreflex sensitivity in humans. To determine whether the two methods produce the same values of baroreceptor sensitivity, we administered intravenous PE by both bolus injection and graded infusion methods to 17 normal subjects. Baroreflex sensitivity was determined from the slope of the linear relationship between the cardiac cycle length (R-R interval) and systolic arterial pressure. Both methods produced similar peak increases in arterial pressure and reproducible results of baroreflex sensitivity in the same subjects, but baroreflex slopes measured by the infusion method (9.9 +/- 0.7 ms/mmHg) were significantly lower than those measured by the bolus method (22.5 +/- 1.8 ms/mmHg, P less than 0.0001). Pretreatment with atropine abolished the heart rate response to PE given by both methods, whereas plasma catecholamines were affected by neither method of PE administration. Naloxone pretreatment exaggerated the pressor response to PE and increased plasma beta-endorphin response to PE infusion but had no effect on baroreflex sensitivity. Thus our results indicate that 1) activation of the baroreflex by the PE bolus and infusion methods, although reproducible, is not equivalent, 2) baroreflex-induced heart rate response to a gradual increase in pressure is less than that seen with a rapid rise, 3) in both methods, heart rate response is mediated by the vagus nerves, and 4) neither the sympathetic nervous system nor the endogenous opiate system has a significant role in mediating the baroreflex control of heart rate to a hypertensive stimulus in normal subjects.

This article has been cited by other articles:

				K. D. Monahan, D. J. Dyckman, and C. A. Ray Effect of acute hyperlipidemia on autonomic and cardiovascular control in humans J Appl Physiol, July 1, 2007; 103(1): 162 - 169. [Abstract] [Full Text] [PDF]

				K. D. Monahan Effect of aging on baroreflex function in humans Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2007; 293(1): R3 - R12. [Abstract] [Full Text] [PDF]

				K. D. Monahan, U. A. Leuenberger, and C. A. Ray Aldosterone impairs baroreflex sensitivity in healthy adults Am J Physiol Heart Circ Physiol, January 1, 2007; 292(1): H190 - H197. [Abstract] [Full Text] [PDF]

				K. D. Monahan and C. A. Ray Cyclooxygenase inhibition and baroreflex sensitivity in humans Am J Physiol Heart Circ Physiol, February 1, 2005; 288(2): H737 - H743. [Abstract] [Full Text] [PDF]

				M. Tanaka and T. Nishikawa Hemodilution Does Not Alter Arterial Baroreflex Control of Heart Rate in Anesthetized Dogs Anesth. Analg., January 1, 2003; 96(1): 28 - 32. [Abstract] [Full Text] [PDF]

				J. Cui, T. E. Wilson, and C. G. Crandall Phenylephrine-induced elevations in arterial blood pressure are attenuated in heat-stressed humans Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2002; 283(5): R1221 - R1226. [Abstract] [Full Text] [PDF]

				K. D. Monahan, F. A. Dinenno, D. R. Seals, C. M. Clevenger, C. A. Desouza, and H. Tanaka Age-associated changes in cardiovagal baroreflex sensitivity are related to central arterial compliance Am J Physiol Heart Circ Physiol, July 1, 2001; 281(1): H284 - H289. [Abstract] [Full Text] [PDF]

				B. E. Hunt, L. Fahy, W. B. Farquhar, and J. A. Taylor Quantification of Mechanical and Neural Components of Vagal Baroreflex in Humans Hypertension, June 1, 2001; 37(6): 1362 - 1368. [Abstract] [Full Text] [PDF]

				C. M. Foley, R. M. McAllister, and E. M. Hasser Thyroid status influences baroreflex function and autonomic contributions to arterial pressure and heart rate Am J Physiol Heart Circ Physiol, May 1, 2001; 280(5): H2061 - H2068. [Abstract] [Full Text] [PDF]

				X.-R. He, W. Wang, J. T. Crofton, and L. Share Effects of 17beta -estradiol on the baroreflex control of sympathetic activity in conscious ovariectomized rats Am J Physiol Regulatory Integrative Comp Physiol, August 1, 1999; 277(2): R493 - R498. [Abstract] [Full Text] [PDF]

				M. H. Hamdan, J. A. Joglar, R. L. Page, J. D. Zagrodzky, C. J. Sheehan, S. L. Wasmund, and M. L. Smith Baroreflex Gain Predicts Blood Pressure Recovery During Simulated Ventricular Tachycardia in Humans Circulation, July 27, 1999; 100(4): 381 - 386. [Abstract] [Full Text] [PDF]

				Y. Nakajima, H. Nose, and A. Takamata Plasma hyperosmolality and arterial pressure regulation during heating in dehydrated and awake rats Am J Physiol Regulatory Integrative Comp Physiol, November 1, 1998; 275(5): R1703 - R1711. [Abstract] [Full Text] [PDF]