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Am J Physiol Regul Integr Comp Physiol. 2015 Jun 1;308(11):R957-64. doi: 10.1152/ajpregu.00525.2014. Epub 2015 Mar 25.

Effects of tempol on baroreflex neural arc versus peripheral arc in normotensive and spontaneously hypertensive rats.

Author information

1
Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and torukawa@ncvc.go.jp.
2
Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and Department of Artificial Organ Medicine, Faculty of Medicine, Osaka University Graduate School of Medicine, Osaka, Japan.
3
Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and.

Abstract

Although oxidative redox signaling affects arterial pressure (AP) regulation via modulation of vascular tone and sympathetic nerve activity (SNA), it remains unknown which effect plays a dominant role in the determination of AP in vivo. Open-loop systems analysis of the carotid sinus baroreflex was conducted to separately quantify characteristics of the neural arc from baroreceptor pressure input to SNA and the peripheral arc from SNA to AP in normotensive Wistar-Kyoto (WKY; n = 8) and spontaneously hypertensive rats (SHR; n = 8). Responses in SNA and AP to a staircase-wise increase in carotid sinus pressure were examined before and during intravenous administration of the membrane-permeable superoxide dismutase mimetic tempol (30 mg/kg bolus followed by 30 mg·kg(-1)·h(-1)). Two-way ANOVA indicated that tempol significantly decreased the response range of SNA (from 89.1 ± 2.4% to 60.7 ± 2.5% in WKY and from 77.5 ± 3.2% to 56.9 ± 7.3% in SHR, P < 0.001) without affecting the lower plateau of SNA (from 12.5 ± 2.4% to 9.5 ± 2.5% in WKY, and from 28.8 ± 2.8% to 30.4 ± 5.7% in SHR, P = 0.800) in the neural arc. While tempol did not affect the peripheral arc characteristics in WKY, it yielded a downward change in the regression line of AP vs. SNA in SHR. In conclusion, oxidative redox signaling plays an important role, not only in the pathological AP elevation, but also in the baroreflex-mediated physiological AP regulation. The effect of modulating oxidative redox signaling on the peripheral arc contributed to the determination of AP in SHR but not in WKY.

KEYWORDS:

carotid sinus baroreflex; equilibrium diagram; open-loop analysis; sympathetic nerve activity

PMID:
25810389
DOI:
10.1152/ajpregu.00525.2014
[Indexed for MEDLINE]
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