The mechanism of ciliary movement. 3. Theory of suppression of reversal by electrical potential of cilia reversed by barium ions.

Abstract

AbstractIt is well known that Paramecium (1) is cathodally galvanotactic in mixtures of sodium and calcium salts because of ciliary reversal at the cathodal end, and that (2) the cilia also may be reversed in solutions rich in monovalent cations or in barium or manganese ions, and (3) the organisms swim backward in these solutions.It also is well known (Kamada, '31) that Paramecium in solutions of barium salts (4) is anodally galvanotactic at low electric potentials, (5) is cathodally galvanotactic at higher potentials, and (6) again becomes anodally galvanotactic if the potential is lowered, but these results have never been explained.However, they can be explained if the membrane is assumed to act as an ion exchanger. Cilia are reversed by barium because barium replaces some of the calcium on the membrane. When a low cathodal potential is applied, the barium, because of its high electrophoretic velocity (Ba++> Ca++> Na+) is removed, thereby causing a suppression of the reversal. If the potential is increased, calcium is also removed, leaving mostly sodium on the membrane, and this causes a return of the reversal. Lowering the potential again causes a suppression of the reversal. Changes at the anodal end can be explained in a comparable manner.