Low levels of cadmium chloride damage the corneal endothelium

The effect of cadmium chloride on the integrity of the endothelium of isolated bullfrog (Rana catesbeiana) corneas was examined by spectrophotometric analysis of corneal uptake of the vital stain Janus green and by scanning electron microscopy (SEM). The uptake of Janus green by the endothelium was dose related between 1.0 and 100.0 mu M CdCl2. The effect of cadmium was significantly attenuated by the calcium channel blocker SKF 96365 and was augmented by the calcium ionophore A23187, indicating that cadmium influx through calcium channels is an important determinant of its cellular effect. The effect of cadmium was not altered by changes in the external calcium concentration, indicating that the mechanism does not involve competitive inhibition by calcium. SEM demonstrated significant structural damage to the corneal endothelium exposed to cadmium chloride, including focal disruption and denuding of the apical endothelial membrane.