Plasma levels of angiotensin II during different penile conditions in the cavernous and systemic blood of healthy men and patients with erectile dysfunction

Objectives. To detect changes in plasma levels of angiotensin II (Ang II) u nder different functional conditions of the penile erectile tissue in the c avernous and systemic blood of patients with erectile dysfunction (ED) and compare them with the course of Ang II in healthy male subjects. It has bee n shown that the mammalian corpus cavernosum produces and secretes physiolo gically relevant amounts of the vasoconstrictive peptide Ang II and that in tracavernosal injection of Ang II terminates penile erection in the dog. Th us, we speculated whether a dysregulation in the secretion or degradation o f Ang II might contribute to the manifestation of ED. Methods. Thirty-four healthy adult men and 48 patients with ED of either or ganogenic or psychogenic etiology were exposed to visual and tactile erotic stimuli to elicit penile tumescence and, in the group of healthy subjects, rigidity. Whole blood was simultaneously aspirated from the corpus caverno sum and the cubital vein during the different functional conditions of the penis. Ang II plasma levels were measured using a radioimmunoassay. Results. In healthy men, the Ang II levels in the cavernous plasma increase d from 22.1 +/- 7.1 pg/mL in the phase of penile rigidity to 27.9 +/- 10 pg /mL in the detumescence phase. In the peripheral plasma, the Ang II levels were 17.2 +/- 6.2 to 19.5 +/- 6.5 pg/mL over the respective penile stages. The courses of Ang II registered in the patients were similar to those dete cted in the healthy men. In the patients and healthy men, systemic Ang II l evels were found to be lower than the concentrations detected in the cavern ous blood. In the group of organogenic patients, the Ang II levels during p enile flaccidity in the systemic and cavernous blood were higher than those registered in the blood samples taken from the healthy men. Conclusions. Our results suggest that cavernous smooth muscle tone is, in p art, balanced by Ang II-induced contraction and that Ang II might be involv ed in the initiation of penile detumescence in men. That Ang II plasma leve ls are generally elevated in the systemic and cavernous blood of patients w ith an organogenic etiology of ED may hint at the significance of Ang II in the pathophysiology of ED. Since the tissue and plasma levels of Ang II ar e regulated by the activity of angiotensin-converting enzyme, there might b e a rationale for the use of angiotensin-converting enzyme inhibitors in th e treatment of vasculogenic ED. (C) 2001, Elsevier Science Inc.