An investigation of some S-nitrosothiols, and of hydroxy-arginine, on the mouse anococcygeus.
1. The effect of five S-nitrosothiols, and of the stereoisomers of NG-hydroxy-arginine (HOARG), were investigated on the mouse anococcygeus. 2. All five S-nitrosothiols produced concentration-related (0.1-100 microM) relaxations of carbachol (50 microM)-induced tone; the order of potency was S-nitroso-L-cysteine (CYSNO) > S-nitroso-N-acetyl-D,L-penicillamine (SNAP) > S-nitrosoglutathione (GSNO) > S-nitrosocoenzyme A (CoASNO) > S-nitroso-N-acetyl-L-cysteine (NACNO). The relaxations were unaffected by the nitric oxide synthase (NOS) inhibitor, L-NG-nitro-arginine (10 microM) (L-NOARG). 3. Cold-storage of the tissue for 72 h resulted in loss of sympathetic and non-adrenergic, non-cholinergic (NANC) nerve function. NOS activity in the tissue was reduced by 97%. Despite this, relaxations induced by the S-nitrosothiols were unaffected. 4. Haemoglobin (50 microM) attenuated relaxations induced by NO and the S-nitrosothiols, although responses to 3-isobutyl-1-methyl-xanthine were unaffected. N-methyl-hydroxylamine (2 mM) which has been shown previously to produce selective inhibition of NANC and nitrovasodilator responses in this tissue, also reduced responses to all S-nitrosothiols. 5. Hydroquinone (100 microM) greatly reduced relaxations to CYSNO (by 88%) but had no effect on those to SNAP, GSNO, CoASNO or NACNO. Since hydroquinone does not reduce responses to NANC stimulation, CYSNO is unlikely to be the NANC transmitter. 6. L-HOARG by itself (up to 100 microM) had no significant effect on carbachol-induced tone or on NANC (10 Hz; 10 strain every 100 s) relaxations. However, it produced reversal of the inhibitory effects of L-NOARG (10;pM), being only slightly less potent than L-arginine. D-HOARG was without effect.L-HOARG had no effect on relaxations induced by 1.51iM NO.7. The results show that S-nitrosothiols are potent relaxants of the mouse anococcygeus; they act directly on the smooth muscle with a mechanism similar to NO and other nitrovasodilators. In addition,the results are consistent with L-HOARG being an intermediate in the biosynthesis of NO from L-arginine, although there is no evidence for it acting to stabilize NO extracellularly.
Gibson
A
A
Smooth Muscle Pharmacology Group, King's College London.
Babbedge
R
R
Brave
S R
SR
Hart
S L
SL
Hobbs
A J
AJ
Tucker
J F
JF
Wallace
P
P
Moore
P K
PK
D000818:Animals; D000963:Antimetabolites / Q000494:pharmacology*; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001341:Autonomic Nervous System / Q000187:drug effects; D002217:Carbachol / Q000494:pharmacology; D003080:Cold Temperature; D006454:Hemoglobins / Q000502:physiology; D006873:Hydroquinones / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008623:Mercaptoethanol; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009132:Muscles / Q000187:drug effects*; D009603:Nitroso Compounds / Q000494:pharmacology*; D026403:S-Nitrosothiols; D013237:Stereoisomerism
D000963:Antimetabolites; D006454:Hemoglobins; D006873:Hydroquinones; D009603:Nitroso Compounds; D026403:S-Nitrosothiols; C007985:N(5)-hydroxy-L-arginine; D008623:Mercaptoethanol; C032635:S-nitrosomercaptoethanol; D002217:Carbachol; D001120:Arginine; C031927:hydroquinone