ADMA and erectile dysfunction

In many patients with erectile dysfunction the L-arginine - NO - cGMP pathway is disturbed [64]. This biochemical defect is often caused by concomitant cardiovascular disease or the presence of cardiovascular risk factors. The molecular relationship between a defect in the NO pathway and the presence of erectile dysfunction forms the background for therapeutic intervention with phosphodiesterase inhibitors like sildenafil (Viagra®), which cause increased cGMP levels and thereby mimic the functional effects of NO.

In recent years several studies have been performed which showed that erectile dysfunction can be restored by supplementation with L-arginine in a subset of patients [65, 66]. Response rates to L-arginine treatment are better when urinary excretion rates of NO metabolites are measured and found to be low before this intervention [66] - which indicates the presence of a biochemical defect in the NO pathway like it can be caused by ADMA.

Recent clinical studies showed that patients with erectile dysfunction on the basis of a concomitant coronary artery disease or diabetes mellitus not only have elevated ADMA concentration, but also decreased L-arginine levels. Thus, the ratio of L-arginine to ADMA is highly unfavourable in these patients. By contrast, in patients with traumatically caused erectile dysfunction no elevation of ADMA was found in comparison to healthy controls.

Quantification of ADMA in plasma or serum of patients with erectile dysfunction may therefore be helpful in discriminating the pathogenesis of erectile dysfunction and in directing patients towards an optimized and individualized therapy.