| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
The Cardiovascular Center and the Departments of Internal Medicine and Physiology & Biophysics, The University of Iowa, Iowa City 52242; and the Department of Veterans Affairs Medical Center, Iowa City, Iowa, 52246
Studies of genetically modified mice provide a powerful approach to investigate consequences of altered gene expression in physiological and pathological states. The goal of the present study was to characterize afferent, central, and efferent components of the baroreceptor reflex in anesthetized Webster 4 mice. Baroreflex and baroreceptor afferent functions were characterized by measuring changes in renal sympathetic nerve activity (RSNA) and aortic depressor nerve activity (ADNA) in response to nitroprusside- and phenylephrine-induced changes in arterial pressure. The data were fit to a sigmoidal logistic function curve. Baroreflex diastolic pressure threshold (Pth), the pressure at 50% inhibition of RSNA (Pmid), and baroreflex gain (maximum slope) averaged 74 ± 5 mmHg, 101 ± 3 mmHg, and 2.30 ± 0.54%/mmHg, respectively (n = 6). The Pth, Pmid, and gain for the diastolic pressure-ADNA relation (baroreceptor afferents) were similar to that observed for the overall reflex averaging 79 ± 9 mmHg, 101 ± 4 mmHg, and 2.92 ± 0.53%/mmHg, respectively (n = 5). The central nervous system mediation of the baroreflex and the chronotropic responsiveness of the heart to vagal efferent activity were independently assessed by recording responses to electrical stimulation of the left ADN and the peripheral end of the right vagus nerve, respectively. Both ADN and vagal efferent stimulation induced frequency-dependent decreases in heart rate and arterial pressure. The heart rate response to ADN stimulation was nearly abolished in mice anesthetized with pentobarbital sodium (n = 4) compared with mice anesthetized with ketamine-acepromazine (n = 4), whereas the response to vagal efferent stimulation was equivalent under both types of anesthesia. Application of these techniques to studies of genetically manipulated mice can be used to identify molecular mechanisms of baroreflex function and to localize altered function to afferent, central, or efferent sites.
pressoreceptors; blood pressure; aortic depressor nerve; sympathetic nerve activity; functional genomics
This article has been cited by other articles:
|
|
 |
|
  X. Shi, F. A. Schaller, N. Tierney, P. Chanthavong, S. Chen, P. B. Raven, and M. L. Smith Physically Active Lifestyle Enhances Vagal-Cardiac Function but Not Central Autonomic Neural Interaction in Elderly Humans Experimental Biology and Medicine, February 1, 2008; 233(2): 209 - 218. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Gu, M. Lin, J. Liu, D. Gozal, K. E. Scrogin, R. Wurster, M. W. Chapleau, X. Ma, and Z. Cheng Selective impairment of central mediation of baroreflex in anesthetized young adult Fischer 344 rats after chronic intermittent hypoxia Am J Physiol Heart Circ Physiol, November 1, 2007; 293(5): H2809 - H2818. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Yu, Z.-H. Zhang, S.-G. Wei, Y. Chu, R. M. Weiss, D. D. Heistad, and R. B. Felder Central Gene Transfer of Interleukin-10 Reduces Hypothalamic Inflammation and Evidence of Heart Failure in Rats After Myocardial Infarction Circ. Res., August 3, 2007; 101(3): 304 - 312. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Lin, R. Liu, D. Gozal, W. B. Wead, M. W. Chapleau, R. Wurster, and Z. Cheng Chronic intermittent hypoxia impairs baroreflex control of heart rate but enhances heart rate responses to vagal efferent stimulation in anesthetized mice Am J Physiol Heart Circ Physiol, August 1, 2007; 293(2): H997 - H1006. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Fazan Jr., M. de Oliveira, V. J. Dias da Silva, L. F. Joaquim, N. Montano, A. Porta, M. W. Chapleau, and H. C. Salgado Frequency-dependent baroreflex modulation of blood pressure and heart rate variability in conscious mice Am J Physiol Heart Circ Physiol, November 1, 2005; 289(5): H1968 - H1975. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. S. Jung, R. Harrison, K. H. Lee, J. Genut, D. Nyhan, E. M. Brooks-Asplund, A. A. Shoukas, J. M. Hare, and D. E. Berkowitz Simulated microgravity produces attenuated baroreflex-mediated pressor, chronotropic, and inotropic responses in mice Am J Physiol Heart Circ Physiol, August 1, 2005; 289(2): H600 - H607. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. A. Townsend, A. S. Jung, Y. S. G. Hoe, R. Y. Lefkowitz, S. A. Khan, C. A. Lemmon, R. W. Harrison, K. Lee, L. A. Barouch, S. Cotecchia, et al. Critical Role for the {alpha}-1B Adrenergic Receptor at the Sympathetic Neuroeffector Junction Hypertension, November 1, 2004; 44(5): 776 - 782. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. B. Persson and J. A. Armour Dual vagal cardiac efferent pathways Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2004; 286(4): R624 - R624. [Full Text] [PDF]
|
|
|
|
|
|
R. L. Davisson Physiological genomic analysis of the brain renin-angiotensin system Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2003; 285(3): R498 - R511. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Ehmke Mouse gene targeting in cardiovascular physiology Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2003; 284(1): R28 - R30. [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
