OSMOTIC SENSITIVITY OF THE HYPERPOLARIZATION-ACTIVATED CL- CURRENT INMOUSE MANDIBULAR DUCT CELLS

We have previously shown that unstimulated mouse mandibular granular d uct cells contain a hyperpolarization-activated Cl- conductance having characteristics similar to those of ClC-2 channels. We now show that exposure of the granular duct cells to hypotonic solutions inhibits th e hyperpolarization-activated Cl- current whereas exposure to hyperton ic solutions causes it to be transiently activated and then inhibited. Like ClC-2 channels in Xenopus oocytes, the hyperpolarization-activat ed Cl- current in mouse granular duct cells is sensitive to osmolality , although its response to osmolality is the reverse of that seen with ClC-2 channels, perhaps due to a difference in the mechanism by which the osmolality signal is transduced to a change in channel activity.