%0 Journal Article %1 Liu_1991_198 %A Liu, Q. Y. %A Strauss, H. C. %D 1991 %J Biophys. J. %K 1883938 Animals, Bilayers, Biological, Calcium, Centrifugation, Channels, Cytoplasm, Density Dogs, Electrophoresis, Gel, Gov't, Gradient, Heart, Lipid Mathematics, Membrane Models, Myocardium, P.H.S., Polyacrylamide Potassium Potentials, Research Reticulum, Sarcoplasmic Solubility, Support, U.S. %N 1 %P 198--203 %T Blockade of cardiac sarcoplasmic reticulum K$^+$ channel by Ca$^2+$: two-binding-site model of blockade. %U http://www.pubmedcentral.gov/articlerender.fcgi?tool=pubmed&pubmedid=1883938 %V 60 %X Potassium countercurrent through the SR K$^+$ channel plays an important role in Ca$^2+$ release from the SR. To see if Ca$^2+$ regulates the channel, we incorporated canine cardiac SR K$^+$ channel into lipid bilayers. Calcium ions present in either the SR lumenal (trans) or cytoplasmic (cis) side blocked the cardiac SR K$^+$ channel in a voltage-dependent manner. When Ca$^2+$ was present on both sides, however, the block appeared to be voltage independent. A two-binding site model of blockade by an impermeant divalent cation (Ca$^2+$) can explain this apparent contradiction. Estimates of SR Ca$^2+$ concentration suggest that under physiological conditions the cardiac SR K$^+$ channel is partially blocked by Ca$^2+$ ions present in the lumen of the SR. The reduction in lumenal Ca$^2+$ during Ca$^2+$ release could increase K$^+$ conductance.

@article{Liu_1991_198, abstract = {Potassium countercurrent through the SR {K}$^{+}$ channel plays an important role in {C}a$^{2+}$ release from the SR. To see if {C}a$^{2+}$ regulates the channel, we incorporated canine cardiac SR {K}$^{+}$ channel into lipid bilayers. Calcium ions present in either the SR lumenal (trans) or cytoplasmic (cis) side blocked the cardiac SR {K}$^{+}$ channel in a voltage-dependent manner. When {C}a$^{2+}$ was present on both sides, however, the block appeared to be voltage independent. A two-binding site model of blockade by an impermeant divalent cation ({C}a$^{2+}$) can explain this apparent contradiction. Estimates of SR {C}a$^{2+}$ concentration suggest that under physiological conditions the cardiac SR {K}$^{+}$ channel is partially blocked by {C}a$^{2+}$ ions present in the lumen of the SR. The reduction in lumenal [{C}a$^{2+}$] during {C}a$^{2+}$ release could increase {K}$^{+}$ conductance.}, added-at = {2009-06-03T11:20:58.000+0200}, author = {Liu, Q. Y. and Strauss, H. C.}, biburl = {https://www.bibsonomy.org/bibtex/25e6196c0457a86c22cc4e05ece1343fc/hake}, description = {The whole bibliography file I use.}, file = {Liu_1991_198.pdf:Liu_1991_198.pdf:PDF}, interhash = {b258d0de719a62edb25dac679175c34b}, intrahash = {5e6196c0457a86c22cc4e05ece1343fc}, journal = {Biophys. J.}, keywords = {1883938 Animals, Bilayers, Biological, Calcium, Centrifugation, Channels, Cytoplasm, Density Dogs, Electrophoresis, Gel, Gov't, Gradient, Heart, Lipid Mathematics, Membrane Models, Myocardium, P.H.S., Polyacrylamide Potassium Potentials, Research Reticulum, Sarcoplasmic Solubility, Support, U.S.}, month = Jul, number = 1, pages = {198--203}, pmid = {1883938}, timestamp = {2009-06-03T11:21:20.000+0200}, title = {Blockade of cardiac sarcoplasmic reticulum {K}$^{+}$ channel by {C}a$^{2+}$: two-binding-site model of blockade.}, url = {http://www.pubmedcentral.gov/articlerender.fcgi?tool=pubmed&pubmedid=1883938}, volume = 60, year = 1991 }