Abstract
The electric resistance of the Millipore DOPH membrane is increased in the mixed salt solution such as KCl and CaCl2, and it oscillates rhythmically under which a current and a pressure stimulus are applied simultaneously. This paper shows electric current (I)-voltage (V) characteristics to derive the plausible mechanism of the resistance oscillation. The current and voltage responses were observed by using the current-voltage clamp circuit which was made by us. The amplitude of the current response increased in proportion to the clamped voltage till 400mV, but above its value the response oscillated. The voltage as well as the current response oscillated also under which the clamped current was kept a value above 0.15μA. These results indicated that it was difficult to describe the oscillation mechanism with a negative conductance as observed in living cell membranes. The Millipore DOPH membrane consists of many small membranes such as oil droplets, spherical micelles and multilayers formed in filter pores. The oscillations observed under clamp conditions were caused by such complex structure. From I-V characteristics, however, it seemed that the oscillation occurred in a single filter pore. Therefore, the structure of the Millipore DOPH membrane could be shown by the simplest model substituted the pore for a capillary. Using the capillary model it could be easily illustrated that the sustained oscillation was caused by the conformational change of the small membrane in one capillary.
