The Effect of pH on the Cyclic GMP-Activated Conductance in Retinal Rods
Cytoplasmic pH effect on the Na+ current through cyclic GM P-activated channels in excised patches from retinal rods of the salamander was studied using rapid solution changes. The current has a plateau from pH 6.7 to 8.2, increases at pH 9.0 and decreases at acidic pH. The shape of the current-voltage relation is unaltered in the range of pH from 5.4 to 9.0 and voltage between −70 and + 70 mV, showing that the effect of cytoplasmic pH is not voltage-dependent. The results are well described assuming that hydrogen ions bind to two charged groups, with apparent pKs of 5.4 and 9.8. Voltage independence of the pH effect suggests that these hydrogen binding sites lie near the inner mouth of the channel.
KeywordsOuter Segment Patch Pipette Membrane Patch Tiger Salamander Magnesium Flux
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