an evidence for a potassium channel in endoplasmic reticulum based on single channel recording in bilayer lipid membrane

introduction numerous studies have demonstrated the presence of potassium selective channels in membranes internal organelles. these channels are essential to a large variety of cellular processes including intracellular 2+ a signaling, protein recycling, charge neutralization and cell protection. in contrast to the sarcoplasmic reticulum + here potassium channels have been clearly identified, there is little evidence for k selective cannels in rer hepatocytes. the aim of this study is to find an evidence for presence of potassium channel in endoplasmic ticulum and considering the pharmacological and biophysical properties of this channel. methods: hepatocytes rer vesicles were isolated by homogenizing rat liver followed by several centrifuging eps and then incorporated into the bilayer lipid membrane (blm). the blm was formed by painting osphatidylcholine across the 350 ?m aperture seperating two chambers (cis chamber containing 200 mm kcl + d trans chamber containing 50 mm kcl). single channel recordings were used to indicate the presence of k annels. results: single channel recordings revealed the existence of a cation selective channel with high permeability + k and 599 ps conductance. the current–voltage relation was linear. the open probability was strongly voltage pendent, showing higher values at positive voltages and lower at negative voltages. a subconductance state out 60 % of fully open state was observed at all voltages. the cationic channel showed an inhibition by 4- + innopyridine (non specific k channel blocker) + conclusions: in this study we have established an evidence for existence of large conductance k channel in e hepatocyte er vesicles.