Galvanotaxic response of tetrahymena vorax

1.1. In electric fields of less than 200 V Tetrahymena vorax exhibited a cathodal galvanotaxic response. This response was analysed for percentage orientation towards the cathode, swimming velocity and the displacement amplitude of the spiralling swimming wave. The three parameters measured were voltage dependent with a lower threshold of 1.5 V.2.2. The forward swimming velocity was inversely proportional to the external [K+]. The amplitude of the swimming wave was reduced in 8mM K+ in electrical fields of both 3 and 40 V. 4-Amino pyridine and tetraethylammonium weakly block gK+ in T. vorax.3.3. An initial decrease in forward swimming velocity in calcium concentrations between 0.125 and 0.25 mM was reversed at higher calcium concentrations reaching a plateau at 1 mM in fields of both 3 and 40 V. The amplitude of the swimming wave showed an inverse relationship to the swimming velocity at similar calcium concentrations.4.4. Procaine reduced the amplitude of the swimming wave at both 3 and 40 V.