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Differences in the dynamic baroreflex characteristics of unmyelinated and myelinated central pathways are less evident in spontaneously hypertensive rats.
- Source :
- American Journal of Physiology: Regulatory, Integrative & Comparative Physiology; Dec2015, Vol. 309 Issue 11, pR1397-R1405, 9p
- Publication Year :
- 2015
-
Abstract
- The aim of the study was to identify the contribution of myelinated (A-fiber) and unmyelinated (Cfiber) baroreceptor central pathways to the baroreflex control of sympathetic nerve activity (SNA) and arterial pressure (AP) in anesthetized Wistar-Kyoto (WKY; n 8) and spontaneously hypertensive rats (SHR; n 8). The left aortic depressor nerve (ADN) was electrically stimulated with two types of binary white noise signals designed to preferentially activate A-fibers (A-BRx protocol) or C-fibers (C-BRx protocol). In WKY, the central arc transfer function from ADN stimulation to SNA estimated by A-BRx showed strong derivative characteristics with the slope of dynamic gain between 0.1 and 1 Hz (G<subscript>slope</subscript>) of 14.63 ± 0.89 dB/decade. In contrast, the central arc transfer function estimated by C-BRx exhibited nonderivative characteristics with G<subscript>slope</subscript> of 0.64 ± 1.13 dB/decade. This indicates that A-fibers are important for rapid baroreflex regulation, whereas C-fibers are likely important for more sustained regulation of SNA and AP. In SHR, the central arc transfer function estimated by A-BRx showed higher G<subscript>slope</subscript> (18.46 ± 0.75 dB/decade, P < 0.01) and that estimated by C-BRx showed higher G<subscript>slope</subscript> (8.62 ± 0.64 dB/decade, P < 0.001) with significantly lower dynamic gain at 0.01 Hz (6.29 ± 0.48 vs. 2.80 ± 0.36%/Hz, P < 0.001) compared with WKY. In conclusion, the dynamic characteristics of the A-fiber central pathway are enhanced in the high-modulation frequency range (0.1-1 Hz) and those of the C-fiber central pathway are attenuated in the lowmodulation frequency range (0.01- 0.1 Hz) in SHR. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 03636119
- Volume :
- 309
- Issue :
- 11
- Database :
- Complementary Index
- Journal :
- American Journal of Physiology: Regulatory, Integrative & Comparative Physiology
- Publication Type :
- Academic Journal
- Accession number :
- 111402539
- Full Text :
- https://doi.org/10.1152/ajpregu.00315.2015