Penicillamine administration reverses the inhibitory effect of hyperhomocysteinaemia on endothelium-dependent relaxation in the corpus cavernosum in the rabbit.
BJU Int
; 98(2): 440-4, 2006 Aug.
Article
em En
| MEDLINE
| ID: mdl-16879692
ABSTRACT
OBJECTIVE:
To elucidate the role of copper in mediating the impact of homocysteine on vasculogenic erectile dysfunction (VED), by investigating the effect of dietary supplementation with the copper-chelator penicillamine to rabbits rendered hyperhomocysteinaemic (HHC) with a methionine-rich diet, as a raised plasma level of homocysteine might be a risk factor for VED. MATERIALS ANDMETHODS:
Homocysteine inhibits the nitric oxide (NO)-dependent relaxation of the corpus cavernosum (CC), an effect which appears to be mediated via the generation of superoxide (O2*-), and H2O2. Copper is a catalyst for the generation of H2O2 in the presence of homocysteine and in the presence of copper, H2O2 undergoes reactions resulting in the generation of O2*-, which reacts with NO to produce peroxynitrite (ONOO-), thereby reducing the bioavailability of NO and impairing NO-mediated relaxation of CC. Smooth muscle strips from CC were obtained from two groups of adult New Zealand White rabbits, one rendered HHC with a diet supplemented with methionine (group 1) and another HHC group that had additional dietary supplementation with penicillamine (group 2). Tissue O2*- levels were measured in each group. After pre-contraction with phenylephrine, relaxation responses of CC strips to carbachol were also assessed in both groups.RESULTS:
Methionine supplementation led to profound HHC in all rabbits. Penicillamine in group 2 reduced the total plasma Cu2+ compared to group 1. There was a markedly lower carbachol-stimulated relaxation of CC from HHC rabbits in group 1, with a mean (sem) maximum relaxation of 37 (4)% (six samples), than in group 2, at 58 (6)%.CONCLUSION:
These data show that elevated levels in vivo of homocysteine in the rabbit markedly impair NO-dependent relaxation of the CC. Furthermore, this effect appears to be augmented by copper. Further clinical studies on homocysteine and copper status in patients with VED are warranted.
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Base de dados:
MEDLINE
Assunto principal:
Penicilamina
/
Pênis
/
Endotélio Vascular
/
Quelantes
/
Hiper-Homocisteinemia
/
Relaxamento Muscular
Tipo de estudo:
Risk_factors_studies
Idioma:
En
Revista:
BJU Int
Ano de publicação:
2006
Tipo de documento:
Article
País de afiliação:
Reino Unido