Changes in phrenic (A) and XII (B) burst amplitudes (% change from baseline) in rats receiving PKA inhibitor +AIH (KT5720, ■, n = 8), vehicle +AIH (saline, ◆, n = 8) and control rats not receiving AIH (i.e., time controls) KT5720 −AIH (□, n = 7) and vehicle −AIH (◇, n = 7). Intrathecal KT5720 augmented phrenic burst amplitude responses following AIH, indicative of enhanced pLTF. However, similar enhancement of XII LTF was not observed, suggesting that drug distribution was restricted to the spinal cord. Values are means±S.E.M. *different than vehicle + AIH, #different than vehicle control, †different than PKA inhibitor control, RMANOVA, p<0.05.