title: Aortic depressor nerve stimulation does not impede the dynamic characteristics of the carotid sinus baroreflex in normotensive or spontaneously hypertensive rats.
abstract: Recent clinical trials in patients with drug-resistant hypertension indicate that electrical activation of the carotid sinus baroreflex can reduce arterial pressure (AP) for more than a year. To examine whether the electrical stimulation from one baroreflex system impedes normal short-term AP regulation via another unstimulated baroreflex system, we electrically stimulated the left aortic depressor nerve (ADN) while estimating the dynamic characteristics of the carotid sinus baroreflex in anesthetized normotensive Wistar-Kyoto (WKY;n= 8) rats and spontaneously hypertensive rats (SHR;n= 7). Isolated carotid sinus regions were perturbed for 20 min using a Gaussian white noise signal with a mean of 120 mmHg for WKY and 160 mmHg for SHR. Tonic ADN stimulation (2 Hz, 10 V, and 0.1-ms pulse width) decreased mean sympathetic nerve activity (73.4 ± 14.0 vs. 51.6 ± 11.3 arbitrary units in WKY,P= 0.012; and 248.7 ± 33.9 vs. 181.1 ± 16.6 arbitrary units in SHR,P= 0.018) and mean AP (90.8 ± 6.6 vs. 81.2 ± 5.4 mmHg in WKY,P= 0.004; and 128.6 ± 9.8 vs. 114.7 ± 10.3 mmHg in SHR,P= 0.009). The slope of dynamic gain in the neural arc transfer function from carotid sinus pressure to sympathetic nerve activity was not different between trials with and without the ADN stimulation (12.55 ± 0.93 vs. 13.03 ± 1.28 dB/decade in WKY,P= 0.542; and 17.37 ± 1.01 vs. 17.47 ± 1.64 dB/decade in SHR,P= 0.946). These results indicate that the tonic ADN stimulation does not significantly modify the dynamic characteristics of the carotid sinus baroreflex.
authors.affiliation: Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan torukawa@ncvc.go.jp.
authors.forename: Toru
authors.initials: T
authors.lastname: Kawada
authors.affiliation: Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Turner
authors.affiliation: Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Shimizu
authors.affiliation: Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Fukumitsu
authors.affiliation: Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan.
authors.forename: Atsunori
authors.initials: A
authors.lastname: Kamiya
authors.affiliation: Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Sugimachi
mesh_terms: D000818:Animals; D001011:Aorta / Q000294:innervation / Q000503:physiopathology*; D017704:Baroreflex; D001794:Blood Pressure; D002346:Carotid Sinus / Q000503:physiopathology*; D004558:Electric Stimulation / Q000379:methods; D025461:Feedback, Physiological; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D014630:Vagus Nerve / Q000503:physiopathology*
keywords: Gaussian white noise; arterial pressure; sympathetic nerve activity; transfer function