%0 Journal Article
%T Central chemoreflex activation induces sympatho©\excitation without altering static or dynamic baroreflex function in normal rats
%A Hiroyuki Tsutsui
%A Kazuya Hosokawa
%A Keita Saku
%A Kenji Sunagawa
%A Masako Shinoda
%A Tadayoshi Miyamoto
%A Takafumi Sakamoto
%A Takeshi Tohyama
%A Takuya Kishi
%A Takuya Nishikawa
%A Yasuhiro Oga
%J Archive of "Physiological Reports".
%D 2017
%R 10.14814/phy2.13406
%X Central chemoreflex activation induces sympatho©\excitation. However, how central chemoreflex interacts with baroreflex function remains unknown. This study aimed to examine the impact of central chemoreflex on the dynamic as well as static baroreflex functions under open©\loop conditions. In 15 anesthetized, vagotomized Sprague©\Dawley rats, we isolated bilateral carotid sinuses and controlled intra©\sinus pressure (CSP). We then recorded sympathetic nerve activity (SNA) at the celiac ganglia, and activated central chemoreflex by a gas mixture containing various concentrations of CO 2. Under the baroreflex open©\loop condition (CSP = 100 mmHg), central chemoreflex activation linearly increased SNA and arterial pressure (AP). To examine the static baroreflex function, we increased CSP stepwise from 60 to 170 mmHg and measured steady©\state SNA responses to CSP (mechanoneural arc), and AP responses to SNA (neuromechanical arc). Central chemoreflex activation by inhaling 3% CO 2 significantly increased SNA irrespective of CSP, indicating resetting of the mechanoneural arc, but did not change the neuromechanical arc. As a result, central chemoreflex activation did not change baroreflex maximum total loop gain significantly (£¿1.29 ¡À 0.27 vs. £¿1.68 ¡À 0.74, N.S.). To examine the dynamic baroreflex function, we randomly perturbed CSP and estimated transfer functions from 0.01 to 1.0 Hz. The transfer function of the mechanoneural arc approximated a high©\pass filter, while those of the neuromechanical arc and total (CSP©\AP relationship) arcs approximated a low©\pass filter. In conclusion, central chemoreflex activation did not alter the transfer function of the mechanoneural, neuromechanical, or total arcs. Central chemoreflex modifies hemodynamics via sympatho©\excitation without compromising dynamic or static baroreflex AP buffering function
%K Arterial pressure regulation
%K carotid sinus baroreflex
%K central chemoreflex
%K sympathetic nerve activity
%U https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5599864/