a new potassium channel on the endoplasmic reticulum membrane in a rat brain: electropharmacology and molecular evidence

Introduction: several types of ion channels found in the plasma membrane have also been identified in the membranes of intracellular organelles. these ion channels, including potassium channels, play a crucial role in regulating intracellular ion homeostasis. an atp-sensitive potassium (katp) channel with various functional roles has been identified in the endo/sarcoplasmic reticulum membranes of both excitable and non-excitable cells. our previous studies investigated the electropharmacological and molecular properties of katp and bkca+2 channels in the rough endoplasmic reticulum (rer) of rat hepatocytes. methods: in this study, for the first time, we described the electropharmacological and molecular properties of the rer katp channel in rat brain cells using an incorporated single-channel in a planar lipid bilayer and western blotting. results: the results of the study revealed the presence of a katp channel with a conductance of 306 ps, and the open probability was found to be voltage-independent at holding potentials ranging from +40 to -60 in an asymmetric solution (200/50 mm kcl; cis/trans). additionally, we observed that adding atp (2.5 mm) to both positive and negative potentials, and 100 μm glibenclamide to the positive voltages inhibited channel activity. the addition of 100 mm 5-hd and 100 nm charybdotoxin to the cis side did not affect the channel behavior. furthermore, a western blot analysis provided evidence of the expression of kir6.2, kir6.1, sulfonylurea receptor (sur)1, and/or sur2b, but not sur2a, in the rer of rat brain fractions.conclusion: in this study, we provide strong evidence for the existence of a katp channel on the rer membrane of rat brain cells, displaying pharmacological properties distinct from those classically described for the plasma membrane and other intracellular organelles.