Factors influencing the vitreous potassium concentration in the rat.

The vitreous of the intact eye of the rate was perfused with artificial medium to study factors that influence the vitreous potassium concentration. The vitreous potassium concentration in anesthetized rats was 5.07 mM. Perfusion with media containing higher or lower potassium concentrations led to passive diffusion of potassium out of or into the vitreous, respectively. Ouabain caused a release of potassium from the retina into the vitreous. Photic stimulation reduced the vitreous potassium concentration, presumably as a result of neuronal hyperpolarization. Glutamate raised and glycine lowered the vitreous potassium concentration, effects that also may be related to retinal depolarization and hyperpolarization, respectively.