Mechanosensitivity of voltage-gated K<SUP>+</SUP> currents in rat trigeminal ganglion neurons

초록

We investigated the mechanosensitivity of voltage-gated K+ channel (VGPC) currents by using whole-cell patch clamp recording in rat trigeminal ganglion (TG) neurons. On the basis of biophysical and pharmacological properties, two types of VGPC currents were isolated. One was transient (I-K,I-A), the other sustained (I-K,I-V). Hypotonic stimulation (200 mOsm) markedly increased both I-K,I-A and I-K,I-V without affecting their activation and inactivation kinetics. Gadolinium, a well-known blocker of mechanosensitive channels, failed to block the enhancement Of I-K,I-A and I-K,I-V induced by hypotonic stimulation. During hypotonic stimulation, cytochalasin D, an actin-based cytoskeletal disruptor, further increased I-K,I-A and I-K,I-V, whereas phalloidin, an actin-based cytoskeletal stabilizer, reduced I-K,I-A and I-K,I-V. Confocal imaging with Texas red-phalloidin showed that actin-based cytoskeleton was disrupted by hypotonic stimulation, which was similar. to the effect of cytochalasin D. Our results suggest that both I-K,I-A and I-K,I-V are mechanosensitive and that actin-based cytoskeleton is likely to regulate the mechanosensitivity of VGPC currents in TG neurons. (c) 2006 Wiley-Liss, Inc.

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