Open AccessHomocysteine and copper interact to promote type 5 phosphodiesterase expression in rabbit cavernosal smooth muscle cells
Author(s) -
Hotston Matthew,
Jeremy Jamie Y.,
Bloor Jonathon,
Greaves Nick S.,
Persad Raj,
Angelini Gianni,
Shukla Nilima
Publication year - 2008
Publication title -
asian journal of andrology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.701
H-Index - 74
eISSN - 1745-7262
pISSN - 1008-682X
DOI - 10.1111/j.1745-7262.2008.00380.x
Subject(s) - apocynin , nicotinamide adenine dinucleotide phosphate , catalase , homocysteine , superoxide , superoxide dismutase , chemistry , biochemistry , endocrinology , phosphodiesterase , oxidase test , cgmp specific phosphodiesterase type 5 , medicine , microbiology and biotechnology , enzyme , sildenafil , biology
Aim: To study the effects of homocysteine and copper on type 5 phosphodiesterase (PDE5) expression in cavernosal vascular smooth muscle cells (CVSMCs) and to investigate superoxide (O 2 ·− ) derived from nicotinamide adenine dinucleotide phosphate oxidase as homocysteine and copper generate O 2 ·− , and O 2 ·− upregulates PDE5 expression. Methods: CVSMCs derived from rabbit penis were incubated with homocysteine or copper chloride with or without superoxide dismutase (SOD), catalase, sildenafil citrate, or apocynin (nicotinamide adenine dinucleotide phosphate inhibitor) for 16 h. The expression of PDE5 and of glyceraldehyde‐3‐phosphate dehydrogenase (internal standard) was assessed using Western blot analysis. In parallel, O 2 ·− was measured spectrophotometrically. Results: CuCl 2 alone (up to 10 μmol/L) and homocysteine alone (up to 100 μmol/L) had no effect on O 2 ·− formation in CVSMCs compared to controls. In combination, however, homocysteine and CuCl 2 markedly increased O 2 ·− formation, an effect blocked by SOD, catalase, apocynin, and sildenafil (1 μmol/L) when co‐incubated over the same time course. PDE5 expression was also significantly increased in CVSMCs incubated with homocysteine and CuCl 2 , compared to controls. This effect was also negated by 16‐h co‐incubation with SOD, catalase, apocynin and sildenafil. Conclusion: This represents a novel pathogenic mechanism underlying ED, and indicates that the therapeutic actions of prolonged sildenafil use are mediated in part through inhibition of this pathway.