Homocysteine and copper interact to promote type 5 phosphodiesterase expression in rabbit cavernosal smooth muscle cells
Article first published online: 11 NOV 2008
© 2008, Asian Journal of Andrology, SIMM and SJTU.
Asian Journal of Andrology
Volume 10, Issue 6, pages 905–913, November 2008
How to Cite
Hotston, M., Jeremy, J. Y., Bloor, J., Greaves, N. S., Persad, R., Angelini, G. and Shukla, N. (2008), Homocysteine and copper interact to promote type 5 phosphodiesterase expression in rabbit cavernosal smooth muscle cells. Asian Journal of Andrology, 10: 905–913. doi: 10.1111/j.1745-7262.2008.00380.x
- Issue published online: 11 NOV 2008
- Article first published online: 11 NOV 2008
- Received 2007-07-03 Accepted 2007-11-25
- erectile dysfunction;
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 (O2·−) derived from nicotinamide adenine dinucleotide phosphate oxidase as homocysteine and copper generate O2·−, and O2·− 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, O2·− was measured spectrophotometrically. Results: CuCl2 alone (up to 10 μmol/L) and homocysteine alone (up to 100 μmol/L) had no effect on O2·− formation in CVSMCs compared to controls. In combination, however, homocysteine and CuCl2 markedly increased O2·− 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 CuCl2, 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.