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 spectroph otometric analysis of corneal uptake of the vital stain Janus green an d 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 importan t determinant of its cellular effect. The effect of cadmium was not al tered by changes in the external calcium concentration, indicating tha t the mechanism does not involve competitive inhibition by calcium. SE M demonstrated significant structural damage to the corneal endotheliu m exposed to cadmium chloride, including focal disruption and denuding of the apical endothelial membrane.