sodium channel

Quick Reference

A cation channel, such as one of the pores in the rods and cones of the retina that is kept open by the substance cyclic GMP and consequently has an unusually low resting potential of approximately −50 millivolts in the dark, but when molecules of visual pigment are stimulated by light they activate the enzyme transducin, which in turn inactivates cGMP so that the pores close and the cell becomes hyperpolarized. See also ion channel, saxitoxin.

Subjects: Chemistry.

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