  A significant part of the thin layers of counter-ions adjacent to the
exterior and interior surfaces of a cell membrane form quasi-two-dimensional
(2D) layers of mobile charge. Collective charge density oscillations, known as
plasmon modes, in these 2D charged systems of counter-ions are predicted in the
present paper. This is based on a calculation of the self-consistent response
of this system to a fast electric field fluctuation. The possibility that the
membrane channels might be using these excitations to carry out fast
communication is suggested and experiments are proposed to reveal the existence
of such excitations.
