Figure 4. Effects of extracellular potassium on the reversal of the photocurrent. (A) Increasing the potassium gradient by lowering [K]o to 2 mM in the presence of normal extracellular Na fails to bring about reversal of the light-evoked current when the membrane is depolarized up to +110 mV. Hesse cell: light stimulus, 6.1 × 1013 photons/cm2. (B) Effect of reducing [K]o on the reversal potential measured in 0 Na. Sodium in the bath solution was replaced by NMDG, and the light response was examined at either 10 mM [K]o (open symbols; traces of bottom right inset) or 2 mM [K]o (closed symbols; top left inset), as the membrane potential was progressively depolarized at 5-mV increments. The reversal potential of the photocurrent shifted by only 2 mV in the negative direction when external potassium was reduced fivefold.
Figure 4.

Effects of extracellular potassium on the reversal of the photocurrent. (A) Increasing the potassium gradient by lowering [K]o to 2 mM in the presence of normal extracellular Na fails to bring about reversal of the light-evoked current when the membrane is depolarized up to +110 mV. Hesse cell: light stimulus, 6.1 × 1013 photons/cm2. (B) Effect of reducing [K]o on the reversal potential measured in 0 Na. Sodium in the bath solution was replaced by NMDG, and the light response was examined at either 10 mM [K]o (open symbols; traces of bottom right inset) or 2 mM [K]o (closed symbols; top left inset), as the membrane potential was progressively depolarized at 5-mV increments. The reversal potential of the photocurrent shifted by only 2 mV in the negative direction when external potassium was reduced fivefold.

This Feature Is Available To Subscribers Only

or Create an Account

Close Modal
Close Modal