Ivabradine does not acutely affect open-loop baroreflex static characteristics and spares sympathetic heart rate control in rats. (15th April 2018)

• Record Type: Journal Article
• Authors: Yamamoto, Hiromi; Kawada, Toru; Shimizu, Shuji; Uemura, Kazunori; Inagaki, Masashi; Kakehi, Kazuyoshi; Iwanaga, Yoshitaka; Fukuda, Kanji; Miyamoto, Tadayoshi; Miyazaki, Shunichi; Sugimachi, Masaru
• Is Part Of: International journal of cardiology. Volume 257(2018)
• Page Start: 255
• Page End: 261
• Publication Date: 2018-04-15
• Subjects: Ivabradine -- Carotid sinus baroreflex -- Open-loop system analysis -- Sympathetic nerve activity -- Heart rate; Cardiology -- Periodicals; Electronic journals; 616.12
• DOI: 10.1016/j.ijcard.2017.11.115
• Languages: English
• ISSNs: 0167-5273

Abstract

Abstract: Aims: To assess the acute effects of intravenous ivabradine, a selective bradycardic agent, on carotid sinus baroreflex-mediated sympathetic arterial pressure (AP) and heart rate (HR) responses. Methods and results: In anesthetized and vagotomized Wistar–Kyoto rats ( n = 6), carotid sinus baroreceptor regions were isolated. Changes in splanchnic sympathetic nerve activity (SNA), AP, and HR in response to a step-wise pressure input were examined before and after intravenous ivabradine (2 mg/kg). Ivabradine did not affect the response range of SNA (91.8 ± 6.5 vs. 93.5 ± 9.8%) or AP (89.6 ± 10.6 vs. 91.0 ± 9.7 mm Hg). Ivabradine significantly reduced the minimum HR from 369.4 ± 8.4 to 223.3 ± 13.2 ( P < 0.001) but did not attenuate the HR response range (69.1 ± 7.0 vs. 82.5 ± 9.6 beats/min). Conclusions: Ivabradine does not acutely affect baroreflex-mediated sympathetic AP regulation and also spares the magnitude of the sympathetic HR response, despite significant bradycardia. The preserved sympathetic HR response, which could not be afforded by beta-blockers, may contribute to some beneficial clinical effects of ivabradine.