 Adenosine modulates the preBötC output via activation of the A1 and A2A receptor subtypes.An adenosine A1 receptor agonist has been shown to depress preBötC rhythmogenesis independent of the neurotransmitters GABA and glycine in in vitro preparations from 0-7 day old mice.Another synthetic drug specific to the adenosine A2A receptor subtype is CGS-21680 that has been shown to cause apneas in 14- to 21-day-old rat pups "in vivo".