Neocuproine, a selective Cu(I) chelator, and the relaxation of rat vascular smooth muscle by S?nitrosothiols

A study has been made of the effect of neocuproine, a specific Cu(I) chelator, on vasodilator responses of rat isolated perfused tail artery to two nitrosothiols: S?nitroso?N?acetyl?d,l?penicillamine (SNAP) and S?nitroso?glutathione (GSNO). Bolus injections (10?l) of SNAP or GSNO (10?7?10?3m) were delivered into the lumen of perfused vessels pre?contracted with sufficient phenylephrine (1?7?m) to develop pressures of 100?120mmHg. Two kinds of experiment were made: SNAP and GSNO were either (a) pre?mixed with neocuproine (10?4m) and then injected into arteries; or (b) vessels were continuously perfused with neocuproine (10?5m) and then injected with either pure SNAP or GSNO. In each case, neocuproine significantly attenuated vasodilator responses to both nitrosothiols, although the nature of the inhibitory effect differed in the two types of experiment. We conclude that the ability of exogenous ?