Glutamatergic neurotransmission in the Locus coeruleus modulates CO2‐drive to breathing

TL;DRAbstract

The Locus coeruleus (LC) has been suggested to be a CO 2 chemoreceptor site in mammals and contains L‐glutamate receptors. In the present study, we assessed the role of glutamatergic receptors in the LC on cardiorespiratory and thermal responses to hypercapnia. Pulmonary ventilation (Ve, plethismography), mean arterial blood pressure (MAP), heart rate (HR) and body temperature (Tb, data loggers) were measured before and after microinjection of kynurenic acid (KYN, an ionotropic glutamatergic receptors antagonist; 5 nmol/100 nL,) and alpha‐methyl‐4‐carboxyphenylglycine (MCPG, a metabotropic glutamatergic receptors antagonist; 10 nmol/100 nL,) into the LC, followed by a 60‐min period of hypercanic exposure (7%CO 2 in air). KYN or MCPG into the LC did not change Ve, MAP, HR and Tb under normocapnia. Hypercapnia caused an increase in Ve, but did not change MAP, HR and Tb. KYN increased the hypercapnic ventilatory response [2269±405 (KYN) vs 1374.2±337 (vehicle) mL kg −1 min −1 ] due to a h

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