Sildenafil (Viagra): is there an influence on psychological performance?

BACKGROUND: Sildenafil (Viagra) is a well-introduced medicine for erectile dysfunction; many studies about effects and side effects are published. Beside these aspects of treatment the influence of sildenafil on psychophysical performance is of interest. cGMP is one of the most important second messengers in the central nervous system (CNS), so even very small changes of the intracellular cGMP-level caused by phosphodiesterases inhibition may be relevant for CNS-function. We wanted to verify the hypothesis whether sildenfail influences human psychomotor performance, especially under the aspect of traffic safety, or not. METHODS: Designed as a pilot study we tested 6 male healthy volunteers using a test battery of 7 different psychophysical performances tests. Each individual did the test battery twice, once without drug and once after a single oral dose of 100-mg sildenafil. 3 persons did the first and 3 others did the second experiment under the influence of drug (UID). All results (37 parameters) were analysed by t-test for paired samples using a confidence interval of 95%. RESULTS: Only two parameters of 2 different tests showed significant differences. In the simple choice reaction test (DR2) the mean reaction time got better in the group with sildenafil; in the multiple choice reaction test with stress induction (RST3) the amount of wrong answers indicated a weak influence of performance without statistical significance, six parameters (dominantly in the speed anticipation test (DEST)) represented an increase and one other (RST3 second part) showed a decrease UID. The uppermost parameters (76% of all items) stayed on equal levels for both groups. CONCLUSION: Sildenafil showed no important impairment of psychophysical performance, no strong improvement was found as well. With a look at the therapeutically indication of sildenafil the improvement in sexual activity may indicate no incapacity in traffic and other psychomotoric/psychophysical functions.

Localization of constitutive nitric oxide synthase isoforms and the nitric oxide target enzyme soluble guanylyl cyclase in the human bladder.

PURPOSE: Nitric oxide is a free radical gas synthesized from L-arginine by a family of isoenzymes called nitric oxide synthase that has an important role in smooth muscle relaxation. L-arginine, the substrate for nitric oxide synthase, may be beneficial under pathophysiological conditions in the bladder, as in interstitial cystitis. We determined the localization of nitric oxide synthase and the target enzyme of NO, soluble guanylyl cyclase, in the human bladder. MATERIALS AND METHODS: Benign bladder tissues were obtained from 18 patients with localized superficial bladder tumors undergoing transurethral bladder resection. Histochemical nicotinamide adenine dinucleotide phosphate-diaphorase staining, nitric oxide synthase immunohistochemical testing and soluble guanylyl cyclase immunoreactivity studies were performed in all benign tissue specimens. RESULTS: A different pattern of nitric oxide synthase expression was confirmed by nicotinamide adenine dinucleotide phosphate-diaphorase staining and immunohistochemical testing for endothelial and neuronal nitric oxide synthase. In addition to endothelial nitric oxide synthase expression, detrusor smooth muscle was recognized as an important location of endothelial nitric oxide synthase, while the urothelium had only small endothelial nitric oxide synthase positive cell clusters. Neuronal nitric oxide synthase expression was only found in nitrinergic fibers of the submucosal surface and between muscle cells. Detrusor and vascular smooth muscle as well as interstitial cells, nerve fibers and transitional epithelium were recognized as targets of nitric oxide, as shown by soluble guanylyl cyclase expression. CONCLUSIONS: The distribution of constitutive nitric oxide synthase isoforms and soluble guanylyl cyclase provides evidence of nitric oxide-cyclic guanosine monophosphate mediated regulation of detrusor smooth muscle relaxation, neurotransmission and blood flow. Furthermore, the urothelium may also be a target of nitric oxide.