Relaxation induced by milrinone and rolipram in human penile arteries and veins.

We studied the relaxant effects of milrinone, an inhibitor of phosphodiesterase 3, and rolipram, an inhibitor of phosphodiesterase 4, on contracted human penile dorsal artery and deep dorsal vein. Vascular rings from 12 multi-organ donors were suspended in organ baths for isometric recording of tension. Both milrinone and rolipram inhibited (100%) the contraction induced by noradrenaline and shifted the relaxation-response curves to the cAMP forming agents prostaglandin E(1) and forskolin to the left. The findings indicate that the cAMP pathway appears to be a main determinant of relaxation in human penile vessels.