| Full text | |
| Author(s): |
Braga, Valdir A.
;
Soriano, Renato N.
;
Machado, Benedito H.
[3]
Total Authors: 3
|
| Document type: | Journal article |
| Source: | Experimental Physiology; v. 91, n. 6, p. 1025-1031, Nov. 2006. |
| Field of knowledge: | Biological Sciences - Physiology |
| Abstract | |
In the present study, we tested the hypothesis that chronic intermittent hypoxia (CIH) produces changes in the autonomic and respiratory responses to acute peripheral chemoreflex activation. To attain this goal, 3-week-old rats were exposed to 10 days of CIH (6% O2 for 40 s at 9 min intervals; 8 h day-1). They were then used to obtain a working heart-brainstem preparation and, using this unanaesthetized experimental preparation, the chemoreflex was activated with potassium cyanide (0.05%, injected via the perfusion system), and the thoracic sympathetic nerve activity (tSNA), heart rate and phrenic nerve discharge (PND) were recorded. Rats subjected to CIH (n = 12), when compared with control animals (n = 12), presented the following significant changes in response to chemoreflex activation: (a) an increase in tSNA (78 ± 4 versus 48 ± 3%); (b) a long-lasting increase in the frequency of the PND at 20 (0.52 ± 0.03 versus 0.36 ± 0.03 Hz) and 30 s (0.40 ± 0.02 versus 0.31 ± 0.02 Hz) after the stimulus; and (c) a greater bradycardic response (-218 ± 20 versus -163 ± 16 beats min-1). These results indicate that the autonomic and respiratory responses to chemoreflex activation in juvenile rats previously submitted to CIH are greatly increased. (AU) | |
| FAPESP's process: | 04/03285-7 - Central mechanisms involved in the sympathoexcitation in response to hypoxia |
| Grantee: | Benedito Honorio Machado |
| Support Opportunities: | Research Projects - Thematic Grants |