Cadmium-induced Decrease in the Outer Facing Skin Resistance of a Bullfrog (Rana catesbeiana)

抄録

Effects of cadmium on the electrical properties of frog skin were investigated by using the microelectrode technique. The epidermal application of 2 mM Cd for 5 min increased both the short circuit current and the skin potential, and decreased the skin resistance (R_M). Cadmium also decreased intracellular potential with reference to the epidermal solution (PD_i) and the electrical resistance between the epidermal solution and the tip of a microelectrode (R_Mi) located in the stratum germinativum.ΔR_M that is R_M, _cd-R_{M, control} seemed to approximately coincide with ΔR_Mi which is R_{Mi, cd}-R_{Mi, control}. Comparing with our previous results, i.e., Cd decreased R_Na (the resistance to the active Na current) and increased RΣ(the resistance to the passive ions) but did not altered E_Na (the electromotive force of active Na current) in the later stage (15 min or later). Cd seemed to decrease the R_Na component at the epidermal side of the skin in the early stage (less than 5 min).