title: Effects of tempol on baroreflex neural arc versus peripheral arc in normotensive and spontaneously hypertensive rats.
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.
authors: Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and torukawa@ncvc.go.jp.
authors: Toru
authors: T
authors: Kawada
authors: 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.
authors: Yusuke
authors: Y
authors: Sata
authors: Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and.
authors: Shuji
authors: S
authors: Shimizu
authors: Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and.
authors: Michael J
authors: MJ
authors: Turner
authors: 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.
authors: Masafumi
authors: M
authors: Fukumitsu
authors: 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.
authors: Masaru
authors: M
authors: Sugimachi
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D062186:Arterial Pressure / Q000187:drug effects; D017704:Baroreflex / Q000187:drug effects*; D002346:Carotid Sinus / Q000187:drug effects* / Q000294:innervation; D003497:Cyclic N-Oxides / Q000494:pharmacology*; D004195:Disease Models, Animal; D006339:Heart Rate / Q000187:drug effects; D006973:Hypertension / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D015398:Signal Transduction / Q000187:drug effects; D013113:Spin Labels; D013564:Sympathetic Nervous System / Q000187:drug effects* / Q000503:physiopathology; D013997:Time Factors
chemical_list: D000959:Antihypertensive Agents; D000975:Antioxidants; D003497:Cyclic N-Oxides; D013113:Spin Labels; C001803:tempol
keywords: carotid sinus baroreflex; equilibrium diagram; open-loop analysis; sympathetic nerve activity