The escape response in zebrafish is mediated in part by the Mauthner cell and its two homologues, MiD2cm and MiD3cm. In adult fish, the Mauthner cell fires a single action potential when activated, while the homologs fire multiple action potentials. Voltage gated potassium channels containing the Kv1.1 subunit have been reported to play roles in modulating the firing properties of neurons. In this study we used a combination of techniques to determine if the Mauthner cells in embryonic zebrafish express Kv1.1. Our results using immunohistochemical and in situ hybridization experiments confirmed the expression of Kv1.1 in zebrafish reticulospinal neurons including the Mauthner cell. Current clamp recordings from the Mauthner cell showed that pharmacological block of Kv1.1 by the specific blocker, Dendrotoxin-K (DTXK), changed its firing properties from the production of a single action potential to firing multiple times. Together, these results suggest that Mauthner cells express potassium channels that contain Kv1.1 subunits, which might contribute to cell firing.
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