Inhibition of Carotid Sinus Baroreflex in Neonatal Rats Exposed to Chronic Intermittent Hypobaric Hypoxia

Peng Xu ； Xue-Bin Cao ； Lu Gao ； Hui-Jie Ma ； Yi Zhang

《The Chinese Journal of Physiology》 57卷6期 (2014/12) Pp. 343-349

https://doi.org/10.4077/CJP.2014.BAD275

並列摘要

Chronic intermittent hypobaric hypoxia (CIHH) facilitates carotid sinus baroreflex (CSB) in adult rats, but the effect of CIHH on CSB in young rats is not known. The purpose of present study was to investigate the effect of CIHH on CSB in the young rat treated with CIHH from neonatal age, and the role of nitric oxide (NO) and Ca^(2+) in the effect of CIHH. Neonatal male Sprague-Dawley rats were randomly divided into three groups: 42-day CIHH treatment group (CIHH42), 56-day CIHH treatment group (CIHH56), and an age-matched control group (control). CIHH neonatal rats with the maternal rats were exposed to a simulated high-altitude hypoxia in a hypobaric chamber mimicking 5,000-m altitude (O_2 at 11.1 %) for 42 or 56 days, 6 h per day, respectively. Isolated carotid sinus perfusion technique was used to test CSB of the rats. After 42-day and 56-day CIHH exposure, the CSB of the rats was inhibited significantly, manifesting as decrease of peak slope (PS) and reflex decrease (RD), and increase of threshold pressure (TP), equilibrium pressure (EP) and saturation pressure (SP). This inhibitory effect was canceled by L-type calcium channel activator Bay K 8644, but not by nitric oxide synthase (NOS) inhibitor N^G-nitro-L-arginine methyl ester (L-NAME). The data showed that CIHH inhibited CSB in anesthetized young rats through blocking L-type calcium channels in carotid sinus baroreceptor.

參考文獻

Gao, L.,Guan, Y.,Cui, F.,Liu, Y.X.,Zhou, Z.N.,Zhang, Y.(2012).Facilitation of chronic intermittent hypobaric hypoxia on carotid sinus baroreflex in anesthetized rats.Chinese J. Physiol..55,62-70.

Béguin, P.C.,Belaidi, E.,Godin-Ribuot, D.,Levy, P.,Ribuot, C.(2007).Intermittent hypoxia-induced delayed cardioprotection is mediated by PKC and triggered by p38 MAP kinase and Erk1/2.J. Mol. Cell. Cardiol..42,343-351.

Béguin, P.C.,Joyeux-Faure, M.,Godin-Ribuot, D.,Levy, P.,Ribuot, C.(2005).Acute intermittent hypoxia improves rat myocardium tolerance to ischemia.J. Appl. Physiol..99,1064-1069.

Behm, R.,Honig, A.,Griethe, M.,Schmidt, M.,Schneider, P.(1984).Sustained suppression of voluntary sodium intake of spontaneously hypertensive rats (SHR) in hypobaric hypoxia.Biomed. Biochem. Acta.43,975-985.

Chapleau, M.W.,Abboud, F.M.(1994).Modulation of baroreceptor activity by ionic and paracrine mechanisms: an overview.Braz. J. Med. Biol. Res..27,1001-1015.