Effects of cadmium ion on the Na,K-ATPase of microsomes obtained from frog skin

Abstract

We have developed a new simple procedure for separating the epidermis from the dermis of the bullfrog (Rana catesbeiana) (freezing and scraping off the skin), and extracting microsomal fraction from the epidermis. The effects of Cd on the ATPase activity of the microsomal fraction was investigated by varying Na and/or K concentrations in the reaction medium. The higher the concentration of Cd, the larger the decreases were found in both activities of ouabain-sensitive ATPase and ouabain-insensitive ATPase in the range of Cd concentration from 10(-7) M to 10(-3) M. The activity of ouabain-sensitive ATPase (Na, K-ATPase) was completely inhibited by 1 mM Cd. The amount of Cd uptake into the whole skin was about 150 micrometer/kg wet weight. This concentration of Cd was sufficient to inhibit the Na, K-ATPase activity of the microsomes. The mechanisms underlying the three types of Cd effects on the frog skin were discussed in relation to the Na, K-ATPase activity.