The influence of zinc gluconate and casein hydrolysate on the fluid and tissue kinetics of zinc-65 in the baboon prostate

The clearance of 65Zn from the bloodstream following an intravenous injection of 65ZnCl2 was significantly delayed by the intravenous administration of stable zinc gluconate 15 min before and the addition of 5% casein hydrolysate to the 65ZnCl2. This resulted in a higher blood 65Zn concentration maintained for a longer period than was the case when only the 65ZnCl2 was injected. The uptake of 65Zn by a number of organs, especially the liver, pancreas, spleen, adrenal, kidney, and caudal prostate, was suppressed by the addition of zinc gluconate and Amigen (5% casein hydrolysate) to the 65ZnCl2. The 65Zn uptake by the skin, testis, epididymis, bladder, and aorta was enhanced by adding zinc gluconate and Amigen to the 65ZnCl2. This also resulted in a raised pancreas/liver ratio. The caudal prostatic 65Zn uptake was significantly suppressed by the use of stable zinc gluconate prior to injection of 65ZnCl2. In both groups the caudal portion of the prostate responded much better to exogenous testosterone than the cranial portion. Zinc gluconate treatment, in general, prevented the rise in prostatic 65Zn uptake observed between the fourth hour and sixth day following the injection of 65ZnCl2. The higher blood 65Zn radioactivity and perhaps the blocking of 65Zn uptake sites in the kidney by stable zinc gluconate resulted in a much higher output of 65Zn in the urine than was the case when only 65 ZnCl2 was used. By the second day, however, the blood and urine concentration of 65Zn had returned to almost ‘normal’ values. The results obtained in this study, using baboons, assume great significance by virtue of their easier application to man than is the case in studies involving rats and dogs. The use of stable zinc gluconate in addition to 65ZnCl2 partially blocked the liver uptake of 65Zn. This may assist in successful pancreatic scanning. The stable zinc gluconate partially blocked the uptake by the prostate of subsequently injected 65Zn.