[Effects of extracellular K+ concentration on the ERG c-wave].

The effects of K+ concentration in the perfusate on ERG were examined in bullfrog neural retina-retinal pigment epithelium-choroid preparations. In the range of K+ concentration between 1.0 and 6.0 mM, an increase in K+ concentration caused a decline in the b-wave amplitude, while leaving the b-wave peak latency almost unchanged. An increase in K+ concentration in the range between 1.0 and 3.0 mM enhanced the c-wave amplitude, while an increase in K+ concentration in the range between 4.0 and 6.0 mM diminished it. An increase in K+ concentration tended to shorten the time course of the c-wave. These results suggest that variations in the K+ concentration in tissue fluid may partially account for the marked inter- and intra-individual variations of the c-wave.