%0 Journal Article %1 Patl_1988_413 %A Patlak, J. B. %D 1988 %J J Gen Physiol %K Analysis Animals; BALB C; Channels, Conductivity; Electric Electrophysiology; Inbred Mathematics; Mice, Mice; Muscles, Piperazines, Sodium Variance; of pharmacology; physiology physiology; %N 4 %P 413--430 %T Sodium channel subconductance levels measured with a new variance-mean analysis. %V 92 %X The currents through single Na+ channels were recorded from dissociated cells of the flexor digitorum brevis muscle of the mouse. At 15 degrees C the prolonged bursts of Na+ channel openings produced by application of the drug DPI 201-106 had brief sojourns to subconductance levels. The subconductance events were relatively rare and brief, but could be identified using a new technique that sorts amplitude estimates based on their variance. The resulting "levels histogram" had a resolution of the conductance levels during channel activity that was superior to that of standard amplitude histograms. Cooling the preparation to 0 degrees C prolonged the subconductance events, and permitted further quantitative analysis of their amplitudes, as well as clear observations of single-channel subconductance events from untreated Na+ channels. In all cases the results were similar: a subconductance level, with an amplitude of roughly 35\% of the fully open conductance and similar reversal potential, was present in both drug-treated and normal Na+ channels. Drug-treated channels spent approximately 3-6\% of their total open time in the subconductance state over a range of potentials that caused the open probability to vary between 0.1 and 0.9. The summed levels histograms from many channels had a distinctive form, with broader, asymmetrical open and substate distributions compared with those of the closed state. Individual subconductance events to levels other than the most common 35\% were also observed. I conclude that subconductance events are a normal subset of the open state of Na+ channels, whether or not they are drug treated. The subconductance events may represent a conformational alteration of the channel that occurs when it conducts ions.

@article{Patl_1988_413, abstract = {The currents through single Na+ channels were recorded from dissociated cells of the flexor digitorum brevis muscle of the mouse. At 15 degrees C the prolonged bursts of Na+ channel openings produced by application of the drug DPI 201-106 had brief sojourns to subconductance levels. The subconductance events were relatively rare and brief, but could be identified using a new technique that sorts amplitude estimates based on their variance. The resulting "levels histogram" had a resolution of the conductance levels during channel activity that was superior to that of standard amplitude histograms. Cooling the preparation to 0 degrees C prolonged the subconductance events, and permitted further quantitative analysis of their amplitudes, as well as clear observations of single-channel subconductance events from untreated Na+ channels. In all cases the results were similar: a subconductance level, with an amplitude of roughly 35\% of the fully open conductance and similar reversal potential, was present in both drug-treated and normal Na+ channels. Drug-treated channels spent approximately 3-6\% of their total open time in the subconductance state over a range of potentials that caused the open probability to vary between 0.1 and 0.9. The summed levels histograms from many channels had a distinctive form, with broader, asymmetrical open and substate distributions compared with those of the closed state. Individual subconductance events to levels other than the most common 35\% were also observed. I conclude that subconductance events are a normal subset of the open state of Na+ channels, whether or not they are drug treated. The subconductance events may represent a conformational alteration of the channel that occurs when it conducts ions.}, added-at = {2009-06-03T11:20:58.000+0200}, author = {Patlak, J. B.}, biburl = {https://www.bibsonomy.org/bibtex/2376a4de5c69e51346ae85b447eafed38/hake}, description = {The whole bibliography file I use.}, file = {Patl_1988_413.pdf:Patl_1988_413.pdf:PDF}, institution = {Department of Physiology and Biophysics, University of Vermont, Burlington 05405.}, interhash = {e769cc44b74b608643013de0cb234564}, intrahash = {376a4de5c69e51346ae85b447eafed38}, journal = {J Gen Physiol}, keywords = {Analysis Animals; BALB C; Channels, Conductivity; Electric Electrophysiology; Inbred Mathematics; Mice, Mice; Muscles, Piperazines, Sodium Variance; of pharmacology; physiology physiology;}, month = Oct, number = 4, pages = {413--430}, pdf = {Patl_1988_413.pdf}, pmid = {2849627}, timestamp = {2009-06-03T11:21:25.000+0200}, title = {Sodium channel subconductance levels measured with a new variance-mean analysis.}, volume = 92, year = 1988 }