Mechanisms involved in aortic baroreceptor excitation during drug-induced aortic pressure elevation in intact rabbits

Yoshitaka Hirooka, Tsutomu Imaizumi, Masaru Sugimachi, Akira Takeshita

Research output: Contribution to journalArticle

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Abstract

Aortic baroreceptor activity during drug-induced elevation of arterial pressure in intact animals is determined not only by the magnitudes of arterial pressure elevation but also by other mechanisms such as the direct effects of drugs on aortic wall property and on baroreceptors per se. This study aimed to determine the relative contribution of arterial pressure elevation and other mechanisms on aortic baroreceptor activity during intravenous infusion of norepinephrine (NE), phenylephrine (PE) or angiotensin II (Ang II) in intact anesthetized rabbits, all of which were used to assess arterial baroreflex function in vivo. We simultaneously recorded aortic pressure (AP), afferent aortic nerve activity (ANA) and the aortic diameter (AD) during elevation of AP induced by intra-aortic balloon inflation or intravenous infusions of NE, PE, and Ang II. During Ang II-infusion or balloon inflation, AD progressively increased with increases in AP. The relationships among changes in AP, ANA, and AD were similar during balloon inflation and during Ang II infusion which indicated that increases in ANA during Ang II infusion were caused by increases in AD or strain of baroreceptors. In contrast, during NE or PE infusion, ANA increased with no changes or decreases in AD, respectively. The latter results suggest that in intact rabbits increases in ANA during NE or PE infusion resulted from mechanisms other than an increase in strain of baroreceptors, such as the direct excitatory effect on baroreceptors. Thus, different mechanisms were involved in aortic baroreceptor excitation in intact rabbits during elevation of AP caused by the vasopressor drugs, which are commonly used to assess arterial baroreflex function in vivo.

Original languageEnglish
Pages (from-to)99-106
Number of pages8
JournalJournal of the Autonomic Nervous System
Volume40
Issue number2
DOIs
Publication statusPublished - Jan 1 1992

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Pressoreceptors
Arterial Pressure
Rabbits
Angiotensin II
Phenylephrine
Pharmaceutical Preparations
Norepinephrine
Economic Inflation
Baroreflex
Intravenous Infusions

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)
  • Physiology
  • Clinical Neurology

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Mechanisms involved in aortic baroreceptor excitation during drug-induced aortic pressure elevation in intact rabbits. / Hirooka, Yoshitaka; Imaizumi, Tsutomu; Sugimachi, Masaru; Takeshita, Akira.

In: Journal of the Autonomic Nervous System, Vol. 40, No. 2, 01.01.1992, p. 99-106.

Research output: Contribution to journalArticle

Hirooka, Yoshitaka ; Imaizumi, Tsutomu ; Sugimachi, Masaru ; Takeshita, Akira. / Mechanisms involved in aortic baroreceptor excitation during drug-induced aortic pressure elevation in intact rabbits. In: Journal of the Autonomic Nervous System. 1992 ; Vol. 40, No. 2. pp. 99-106.
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