Penetration of 65Zn through the skin of rats

A study has been made of the penetration of 65Zn from various zinc chloride solutions, from a zinc oxide suspension and from a zinc tape containing zinc oxide through the intact skin of rats. 65Zn rapidly appeared in the blood and other tissues. The maximum 65Zn activity in serum occurred within or around the first hour after the application of both zinc chloride and zinc oxide almost completely independent of the zinc concentration applied and the pH. A greater total penetration of 65Zn was found from a carrier-free 65Zn-zinc chloride solution at pH 1 than from the same solution made less acidic (pH 4) and from a zinc oxide suspension at pH 8 (125 microgram Zn/ml). The 65 Zn penetration from the carrier-free solution was slightly (though not significantly) higher than that from the same solution with zinc chloride added to bring the total zinc concentration to 125 microgram/ml. Autoradiographically, 65Zn activity was seen in both dermis and panniculus carnosus. The activity was most concentrated on and near the epidermis and around hair follicles in dermis. No differences were observed between animals treated with zinc chloride (pH 1 and pH 4) and animals treated with a zinc oxide suspension.