Light and dark adaptation of crayfish visual cells depending on extracellular calcium concentration.

Lowering of extracellular Ca2+-concentration from 14 X 10(-3) M to ca. 10(-6) M (using 1 mM ethyleneglycol bis (beta-aminoethylether)-N,N'-tetraacetic acid (EGTA)) results in weaker light adaptation by a 2 s light exposure and faster dark adaptation (half time 45 +/- 1%) of crayfish visual cells.