Effect of cadmium on the isolated vas deferens from guinea-pig

The effects of cadmium on the responses to the agonists, K, acetylcholine, noradrenaline, Ba and Ca were investigated in the isolated vas deferens from guinea pig. 1. The low concentration of cadmium enhanced the effects of tested agonists, and the enhancement was larger in order of K, Ba, Ca, noradrenaline=acetylcholine. 2. The high concentration of cadmium inhibited the effects of tested agonists with a dose-dependent manner. The inhibitory effect was weaker against the contraction by K and was stronger against the contractions by Ba, Ca, acetylcholine and noradrenaline. 3. The inhibitory effects of cadmium against the contractions by acetylcholine and noradrenaline were almost the same. 4. On the shape of contraction by K, cadmium showed the stronger inhibition against the tonic contraction than the phasic contraction. 5. The above mentioned results were mainly discussed on the Ca mobilization and the receptor selectivity.