Serotonin 2A and 2B receptor-induced phrenic motor facilitation: differential requirement for spinal NADPH oxidase activity

▶Episodic activation of cervical spinal serotonin (5-HT) receptor types 2A and 2B elicits facilitation (pMF) of phrenic nerve activity. ▶Initiation of pMF by 5-HT2B receptor activation requires spinal NADPH oxidase activity. ▶Phrenic motor neurons contain both 5-HT2A and 5-HT2B receptors.