Effects of Cu~(2+), Zn~(2+) and Mn~(2+)on postsynaptic sites / 中国药理学通报

ABSTRACT

Effects of Cu2+,Zn2+and Mn2+ on responses to ACh were studied with toad rec-tus abdominis. Cu2+, Zn2+and Mn2+concentra-tion- dependently shifted the concentration-response curves for ACh to the right unparallelly and reduced the maximal response considerably. The pAh values of Cu2+ , Zn2+ and Mn2+ were 3.69, 2.95 and 2. 62, respectively. The inhibitory potent of Cu2+ and Zn2+ seemed to be 11.7 times and 2. 1 times respectively more thanthat of Mn2+. It was suggested that Cu2+, Zn2+ and Mn2+postsynaptically interfere with the action of ACh. However, Zn2+in lower concentration shifted the bottom section of the curve for ACh to the left and top, and shifted the top section of the curve to the right, suggesting that Mn2+in lower concentration be possessed of partial agonistic property.