A Geometric Sequence that Accurately Descrbes Allowed Multiple Conductance Levels of Ion Channels: The "Three Halves

Ion chaniels can express multiple cornuctance lvels that are not integer multiples of some unilary coructance, andtt interconvertamong oneanr. We report here hat for26 different types of multie conctncedecannels, al alowed conductarnc levels can be accurately using the geometr quec = and n is an integer .0. We refer to this relatonshp as the % Rule,w the value of any term in the sequence of conductac (g) can be calculted as times the value of the proceeding term (9The experimentally determied average value for *' is 1.491 + 0.095 (sample size = 37, average + SD). We also veriFy the choice of a* ratio on the basis of error analysis over the range of ratio values betwen 1.1 and 2.0. In an independent analysis using Marquardt's alngorIth, we further verified the* ratio and the assonent of specfi coductces to specific terms in the geetric sequence. Thus, irpecive of the open time , the alowed conductance levels of these chanels can be descrbed accurately to within -6%. We anticiate that the Rtue' will simplify descripin of mulie conductance channels in a wide variety of bilogical systems and provide an organng for chanel hetogenelty and dilfe l effects of channel blockers.