Activation of central adenosine A2A receptors enhances superior laryngeal nerve stimulation-induced apnea in piglets via a GABAergic pathway

Activation of the laryngeal mucosa results in apnea that is mediated through, and can be elicited via electrical stimulation of, the superior laryngeal nerve (SLN). This potent inhibitory reflex has been suggested to play a role in the pathogenesis of apnea of prematurity and sudden infant death syndrome, and it is attenuated by theophylline and blockade of GABAA receptors. However, the interaction between GABA and adenosine in the production of SLN stimulation-induced apnea has not been previously examined. We hypothesized that activation of adenosine A2A receptors will enhance apnea induced by SLN stimulation while subsequent blockade of GABAA receptors will reverse the effect of A2A receptor activation. The phrenic nerve responses to increasing levels of SLN stimulation were measured before and after sequential intracisternal administration of the adenosine A2A receptor agonist CGS (n = 10) and GABAA receptor blocker bicuculline (n = 7) in ventilated, vagotomized, decerebrate, and paralyzed newborn pig...