Role of copper in the relaxant action of S-nitrosothiols in the rat anococcygeus muscle.
1. The effects of copper chelators were investigated on the relaxant actions of the S-nitrosothiols S-nitrosoglutathione (GSNO) and S-nitroso-N-acetyl-d,l-penicillamine (SNAP), the non-S-nitrosothiol nitric oxide (NO) donor sodium nitroprusside (SNP), free radical NO (NO.) and the nitrergic neurotransmitter in rat isolated anococcygeus muscle. 2. Cumulative additions of GSNO (0.01-100 micro mol/L), SNAP (0.001-10 micro mol/L), SNP (0.001-1 micro mol/L) and NO. (0.5-5 micro mol/L) and electrical field stimulation (EFS; 1-5 Hz, 10 s) of nitrergic nerves in preparations precontracted with guanethidine (10-30 micro mol/L) and clonidine (0.01-0.3 micro mol/L) produced concentration-dependent relaxations. 3. The Cu[I] chelator neocuproine (10-30 micro mol/L) produced concentration-dependent inhibitions of the relaxations to GSNO and SNAP. At 30 micro mol/L, neocuprinone had no effect on relaxations to SNP (0.001-1 micro mol/L), NO. (0.5-5 micro mol/L) or EFS (1-5 Hz, 10 s). 4. The Cu[II] chelator cuprizone (30 micro mol/L) slightly and significantly enhanced relaxations to GSNO and NO., but had no effect on relaxations to SNAP, SNP or EFS. 5. In conclusion, the results indicate that Cu[I], but not Cu[II], may be involved in the relaxant actions of GSNO and SNAP in the rat anococcygeus muscle.
Ng
Chi Wai
CW
School of Medical Sciences, Division of Biosciences, RMIT University, Melbourne, Victoria, Australia.
Najbar-Kaszkiel
Alicja T
AT
Li
Chun Guang
CG
D001003:Anal Canal / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D002614:Chelating Agents / Q000494:pharmacology; D003300:Copper / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects* / Q000502:physiology; D026602:Nitrergic Neurons / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D026403:S-Nitrosothiols / Q000494:pharmacology*; D012445:Sacrococcygeal Region / Q000502:physiology
D002614:Chelating Agents; D026403:S-Nitrosothiols; D003300:Copper