Effect of neocuproine, a selective Cu(I) chelator, on nitrergic relaxations in the mouse corpus cavernosum

The effects of neocuproine and bathocuproine, Cu(I) and Cu(II) chelators, r espectively, were studied on relaxations in response to electrical field st imulation, acetylcholine, S-nitrosoglutathione, acidified sodium nitrite an d sodium nitroprusside in the mouse corpus cavernosum precontracted with ph enylephrine. Neocuproine significantly inhibited relaxations induced by ele ctrical field stimulation, acetylcholine and S-nitrosoglutathione, but not by acidified sodium nitrite and sodium nitroprusside. The pre-prepared neoc uproine-Cu(I) complex was ineffective on the responses. The discrepancy bet ween the shape of relaxations in response to electrical field stimulation o r to acetylcholine and S-nitrosoglutathione was abolished by adding CuCl2 i nto the bathing medium. The copper action was blocked by neocuproine but no t by bathocuproine. However, the pre-prepared bathocuproine-Cu(II) complex did not accelerate the relaxations affected by CuCl2. These findings sugges t that a Cu(I)-dependent mechanism may play a role in the relaxation induce d by the endogenous relaxant factor as well as by S-nitrosoglutathione in m ouse cavernosal tissue. (C) 2000 Elsevier Science B.V. All rights reserved.