Evidence for water-permeable channels in auditory hair cells in the leopard frog

► Aquaporin-4 immunoreactivity is found in the amphibian papilla in the frog inner ear. ► Isolated amphibian papillar hair cells show AQP4 immunoreactivity along the plasmalemma. ► Previous estimates of permeability coefficients for amphibian papillar hair cells were confirmed. ► Water channels may mark a physiological difference between amphibians and mammals.