The impact of volume loading–induced low pressure baroreflex activation on arterial baroreflex-controlled sympathetic arterial pressure regulation in normal rats

Yasuhiro Oga, Keita Saku, Takuya Nishikawa, Takuya Kishi, Tomoyuki Tobushi, Kazuya Hosokawa, Takeshi Tohyama, takafumi sakamoto, Kenji Sunagawa, Hiroyuki Tsutsui

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Abstract

Although low pressure baroreflex (LPB) has been shown to elicit various cardiovascular responses, its impact on sympathetic nerve activity (SNA) and arterial baroreflex (ABR) function has not been fully elucidated. The aim of this study was to clarify how volume loading-induced acute LPB activation impacts on SNA and ABR function in normal rats. In 20 anesthetized Sprague-Dawley rats, we isolated bilateral carotid sinuses, controlled carotid sinus pressure (CSP), and measured central venous pressure (CVP), splanchnic SNA, and arterial pressure (AP). We infused blood stepwise (3 mL/kg/step) to activate volume loading-induced LPB. Under the ABR open-loop condition, stepwise volume loading markedly increased SNA by 76.8 ± 21.6% at CVP of 3.6 ± 0.2 mmHg. In contrast, further volume loading suppressed SNA toward the baseline condition. Bilateral vagotomy totally abolished the changes in SNA by volume loading. To assess the impact of LPB on ABR function, we changed CSP stepwise. Low volume loading (CVP = 3.6 ± 0.4 mmHg) significantly shifted the sigmoidal CSP–SNA relationship (central arc) upward from baseline, whereas high volume loading (CVP = 5.4 ± 0.4 mmHg) returned it to the baseline level. Volume loading shifted the linear SNA–AP relationship (peripheral arc) upward without significant changes in slope. In conclusions, volume loading-induced acute LPB activation evoked two-phase changes, an initial increase followed by decline from baseline value, in SNA via resetting of the ABR central arc. LPB may contribute greatly to stabilize AP in response to volume status.

Original languageEnglish
Article numbere13887
JournalPhysiological Reports
Volume6
Issue number19
DOIs
Publication statusPublished - Sep 1 2018

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Baroreflex
Arterial Pressure
Pressure
Central Venous Pressure
Carotid Sinus
Splanchnic Nerves
Vagotomy
Sprague Dawley Rats

All Science Journal Classification (ASJC) codes

  • Physiology
  • Physiology (medical)

Cite this

The impact of volume loading–induced low pressure baroreflex activation on arterial baroreflex-controlled sympathetic arterial pressure regulation in normal rats. / Oga, Yasuhiro; Saku, Keita; Nishikawa, Takuya; Kishi, Takuya; Tobushi, Tomoyuki; Hosokawa, Kazuya; Tohyama, Takeshi; sakamoto, takafumi; Sunagawa, Kenji; Tsutsui, Hiroyuki.

In: Physiological Reports, Vol. 6, No. 19, e13887, 01.09.2018.

Research output: Contribution to journalArticle

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abstract = "Although low pressure baroreflex (LPB) has been shown to elicit various cardiovascular responses, its impact on sympathetic nerve activity (SNA) and arterial baroreflex (ABR) function has not been fully elucidated. The aim of this study was to clarify how volume loading-induced acute LPB activation impacts on SNA and ABR function in normal rats. In 20 anesthetized Sprague-Dawley rats, we isolated bilateral carotid sinuses, controlled carotid sinus pressure (CSP), and measured central venous pressure (CVP), splanchnic SNA, and arterial pressure (AP). We infused blood stepwise (3 mL/kg/step) to activate volume loading-induced LPB. Under the ABR open-loop condition, stepwise volume loading markedly increased SNA by 76.8 ± 21.6{\%} at CVP of 3.6 ± 0.2 mmHg. In contrast, further volume loading suppressed SNA toward the baseline condition. Bilateral vagotomy totally abolished the changes in SNA by volume loading. To assess the impact of LPB on ABR function, we changed CSP stepwise. Low volume loading (CVP = 3.6 ± 0.4 mmHg) significantly shifted the sigmoidal CSP–SNA relationship (central arc) upward from baseline, whereas high volume loading (CVP = 5.4 ± 0.4 mmHg) returned it to the baseline level. Volume loading shifted the linear SNA–AP relationship (peripheral arc) upward without significant changes in slope. In conclusions, volume loading-induced acute LPB activation evoked two-phase changes, an initial increase followed by decline from baseline value, in SNA via resetting of the ABR central arc. LPB may contribute greatly to stabilize AP in response to volume status.",
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