| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Biomolecular Science Center, University of Central Florida, Orlando, Florida, United States
2 1Biomolecular Science Center, Burnett College of Biomedical Sciences, University of Central Florida, Orlando, Florida, United States
3 Kosair Children's Hospital Research Institute, Department of Pediatrics, University of Louisville School of Medicine, Louisville, Kentucky, United States
4 Pharmacology and Experimental Therapeutics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, United States
5 Physiology, Loyola University, Maywood, Illinois, United States
6 College of Medicine, University of Iowa, Iowa City, Iowa, United States
7 Internal Medicine, University of Iowa, College of Medicine, Iowa City, Iowa, United States
* To whom correspondence should be addressed. E-mail: zcheng{at}mail.ucf.edu.
Baroreflex control of heart rate (HR) is impaired following chronic intermittent hypoxia (CIH). However, the location and nature of this response remain unclear. We examined baroreceptor afferent, vagal efferent, and central components of the baroreflex circuitry. Fischer 344 (F344) rats were exposed to room air (RA) or CIH for 35-50 days, and were then anesthetized with isoflurane, ventilated, and catheterized for measurement of mean arterial blood pressure (MAP) and HR. Baroreceptor function was characterized by measuring percent (%) changes of integrated aortic depressor nerve activity (Int ADNA) relative to the baseline value in response to nitroprusside- and phenylephrine-induced changes in MAP. Data were fitted to a sigmoid logistic function curve. Heart rate responses to electrical stimulation of the left aortic depressor nerve and the right vagus nerve were assessed under ketamine-acepromazine anesthesia. Compared to RA controls, CIH significantly increased maximum baroreceptor gain or maximum slope (Gmax), maximum Int ADNA, and Int ADNA range (maximum - minimum ADNA), whereas other parameters of the logistic function were unchanged. In addition, CIH increased the maximum amplitude of bradycardic response to vagal efferent stimulation and decreased the time from the stimulus onset to the peak response. In contrast, CIH significantly reduced the maximum amplitude of bradycardic response to left aortic depressor nerve stimulation and increased the time from the stimulus onset to the peak response. Therefore, CIH decreased central mediation of the baroreflex, but augmented baroreceptor afferent function and vagal efferent control of HR.
This article has been cited by other articles:
|
|
 |
|
  D. B. Zoccal, L. G. H. Bonagamba, J. F. R. Paton, and B. H. Machado Sympathetic-mediated hypertension of awake juvenile rats submitted to chronic intermittent hypoxia is not linked to baroreflex dysfunction Exp Physiol, September 1, 2009; 94(9): 972 - 983. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. Yan, L. Li, S. W. Harden, D. Gozal, Y. Lin, W. B. Wead, R. D. Wurster, and Z. Cheng Chronic intermittent hypoxia impairs heart rate responses to AMPA and NMDA and induces loss of glutamate receptor neurons in nucleus ambiguus of F344 rats Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2009; 296(2): R299 - R308. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
