AMPA/Kainate receptors mediate sympathetic chemoreceptor reflex in the rostral ventrolateral medulla

Miyawaki, T.; Minson, J.; Arnolda, L.; Llewellyn-Smith, I.; Chalmers, J.; Pilowsky, P.

Brain Research 726(1-2): 64-68


ISSN/ISBN: 0006-8993
PMID: 8836546
DOI: 10.1016/0006-8993(96)00272-7
Accession: 008087539

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Previous studies have reported that information from carotid chemoreceptors activates sympathetic premotor neurons in the rostral ventrolateral medulla (RVLM) exclusively via N-methyl-D-aspartic acid (NMDA) receptors. In this study, we examined the possible involvement of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptors in the RVLM on sympathetic chemoreceptor reflex in pentobarbitone anaesthetized, vagotomized and artificially ventilated rats. Carotid chemoreceptor stimulation with brief N-2 inhalation increased splanchnic sympathetic nerve activity and arterial pressure in animals that had received an intravenous injection of the non-competitive NMDA receptor blocker, MK-801 (2 mg/kg). RVLM sympathetic premotor neurons could also be activated by brief hypoxia in the presence of MK-801. However, microinjection of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, a selective AMPA/kainate receptor antagonist, 2 mM, 100 nl) into the RVLM after intravenous MK-801 abolished the hypoxia evoked sympathoexcitatory response. These results demonstrate that AMPA/kainate receptors in the RVLM are involved in the chemoreceptor reflex pathway.