Time course of the spasmolytic effect of cadmium and cadmium uptake in guinea-pig taenia coli

o 1. 1. The relationship between tension inhibitory action of cadmium and cadmium uptake was investigated in the smooth muscle of taenia coli. 2. 2. Following a treatment with 0.5 mM Cd 2+ for short periods (1, 5 min), the tension to high-K + returned to a greater extent after washing with disodium edetate (EDTA) or cysteine, compared to normal medium. 3. 3. However, the restored tension to the high-K + decreased with increasing duration of Cd 2+ treatment. 4. 4. With a longer duration of 0.5 mM Cd 2+ treatment, the cadmium uptake increased and the size of cadmium fraction bound to cells firmly increased. 5. 5. It is suggested that Cd 2+ binds initially to the surface membrane of taenia coli and that Cd 2+ subsequently migrates to a compartment that EDTA cannot reach.