The effects of systemic LPS on pLTF, with and without a known microglial inhibitor (minocycline). Both LPS and minocycline diminish AIH-induced pLTF. A) Compressed phrenic neurograms from in vivo anesthetized, vagotomized, paralyzed, ventilated rats demonstrating typical AIH-induced pLTF (upper trace), and reduced pLTF 3 hrs post-LPS (3 mg/kg, i.p.; lower trace). B) Group data demonstrating significant reduction in pLTF with LPS, LPS and minocycline (30 mg/kg, i.v.) and minocycline alone. (** p<0.01, *** p<0.001 indicates significant difference from vehicle response). Statistics: one-way ANOVA with Fisher's LSD post hoc test.