In control rats, moderate AIH (i.e., 35–55 mmHg PaO2) elicits pLTF through Gq-dependent mechanisms via serotonin two receptors (5-HT2) in the phrenic motor nucleus (Bach and Mitchell, 1996; Baker-Herman et al., 2004; Hoffman et al., 2012; Devinney et al., 2013; Devinney et al., 2015), while severe AIH (i.e., 25–35 mmHg PaO2) elicits enhanced pLTF through a different pathway using Gs-dependent mechanisms and adenosine (A2A) receptors (Golder et al., 2008; Nichols et al., 2012; Devinney et al., 2013; Agosto-Marlin and Mitchell, 2017). The gene discussed is HTR2A; the disease is autoimmune hepatitis.