Effects of low [Ca2+]0 upon [K+]0 during and after maintained illumination of the isolated retina of the toad.
Using K+-selective microelectrodes, [K+]0 was measured in the receptor layer of the isolated retina of the toad, Bufo marinus, during and after maintained adapting illumination. Lowering [Ca2+]0 to one-tenth of its control value produced larger, more rapid changes in [K+]0 at light onset and offset than under control conditions. Lowering [Ca+]0 also produced rod membrane depolarization in the dark and larger light-evoked changes in rod membrane voltage. The observed effects are consistent with a mechanism by which lowering [Ca+]0 increases sodium conductance in rods in the dark, which in turn increases [Na+]i and stimulates the rods' NA+/K+ pump. This putative mechanism may be used to explain several effects of low [Ca+]0 upon rod function observed previously.
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002024:Bufo marinus; D002118:Calcium / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005074:Evoked Potentials, Visual / Q000187:drug effects; D066298:In Vitro Techniques; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*
D011188:Potassium; D002118:Calcium