AQP4 and infectious otitis media: The level of AQP4 M1 isoform mRNA decreased by 47% (from 1.03 ± 0.28% in control to 0.56 ± 0.19) at 24 h post-AOM (n = 7 and 3 in control and AOM-injected, respectively), whereas AQP4 M23 isoform mRNA dropped by 96% (from 1.035 ± 0.3 in control, to 0.04 ± 0.02) at 12 h (n = 7 and 5 in control and AOM-injected, respectively), rose back to the control level at 18 h (n = 7 and 3 in control and AOM-injected, respectively), and decreased again by 57% (to 0.44 ± 0.05) at 24 h (n = 7 and 3 in control and AOM-injected, respectively) (Fig. 3A).