1.  We have formulated a theory for understanding the effect of an oscillating or fluctuating membrane potential on the structure and function of membrane protein.  In particular, implications concerning the mechanisms of biological signal and transduction have been explored.  2.  An apparatus, designed and constructed in conjunction with BEIB, has been developed for the purpose of experimentally testing the above theories.  The device allows for the application of an oscillating electric field across a suspension of cell with an amplitude up to plus or minus 150 V/cm (plus or minus 1000 V/cm in a different mode) with a very flexible wave shape.  Preliminary experiments indicate that indeed there is a non- ohmic response of cell suspensions to an increase in the field amplitude.  The frequency dependence can also be determined.