Accumulation and toxicity of gold in the rabbit lens in vitro

Gold compounds are used therapeutically and have been observed to accumulate in the human eye. In the present study, we have measured the accumulation and loss of gold (AuIII) in rabbit lenses in vitro using 195Au as a tracer. Accumulation increased progressively with time of incubation up to 24 hr. The highest concentration of Au3+ observed was about 16 mumol kg-1 wet wt. Rate of accumulation also rose with increase in the external concentration of Au3+, but the magnitude of the change exceeded the concentration difference. Autoradiography showed a high accumulation of 195Au in a central region of the anterior face of the lens, as has been observed in vivo in humans undergoing chrysotherapy. Loss (efflux) of accumulated 195Au was increased by the presence of Au3+ or dithiothreitol in the external media. Lanthanum (La3+), however, decreased the loss of such Au and promoted its accumulation. Gold can have a toxic effect on lenses as incubation for 7 days in a medium containing 10(-7) M Au3+ resulted in a marked gain of Na and loss of K. The results suggest that Au accretion occurs at surface sites associated with the anterior of the lens, but whether or not intracellular accumulation occurs is not clear. This Au, in excess, may have toxic effects on the tissue.