BARRIER FLUCTUATIONS AND STOCHASTIC RESONANCE IN MEMBRANE-TRANSPORT

The role of barrier fluctuations in membrane enzymatic processes, in p articular in the active transport of ions through cell membranes, is e xamined. For enzymes embedded in the cell membrane the role of the bar rier height (activation energy) is played by the membrane electric pot ential. This barrier height can be modulated either by internal fluctu ations or by external electrical fields, either random or periodic. Ex isting experimental data on active transport of Na+ and Rb+ in human e rythrocytes (catalyzed by Na+-K+-ATPase:) call be interpreted as evide nce of stochastic resonance between the external ac field and the fluc tuations of the membrane potential. The obtained results suggest that the significant part of these fluctuations is supplied by the stimulat ed action of neighbor voltage-gated ionic channels. This supports the idea that intrinsic noise plays a constructive role in one of most imp ortant and most frequent biophysical processs, viz. ion transmission t hrough cell membranes.;Means of further experimental verification of t his conjecture are proposed. (C) 1998 American Institute of Physics.