Role of intracellular Ca2+ stores in smooth muscle of human penile erectile tissue

Dynamic erectile responses of a novel penile organ model utilizing TPEM†

Male penis is required to become erect during copulation. In the upper (dorsal) part of penis, the erectile tissue termed corpus cavernosum (CC) plays fundamental roles for erection by regulating the inner blood flow. When blood flows into the CC, the microvascular complex termed sinusoidal space is reported to expand during erection. A novel in vitro explant system to analyze the dynamic erectile responses during contraction/relaxation is established. The current data show regulatory contraction/relaxation processes induced by phenylephrine (PE) and nitric oxide (NO) donor mimicking dynamic erectile responses by in vitro CC explants. Two-photon excitation microscopy (TPEM) observation shows the synchronous movement of sinusoidal space and the entire CC. By taking advantages of the CC explant system, tadalafil (Cialis) was shown to increase sinusoidal relaxation. Histopathological changes have been generally reported associating with erection in several pathological conditions. Various stressed statuses have been suggested to occur in the erectile responses by previous studies. The current CC explant model enables to analyze such conditions through directly manipulating CC in the repeated contraction/relaxation processes. Expression of oxidative stress marker and contraction-related genes, Hypoxia-inducible factor 1-alpha (Hif1a), glutathione peroxidase 1 (Gpx1), Ras homolog family member A (RhoA), and Rho-associated protein kinase (Rock), was significantly increased in such repeated contraction/relaxation. Altogether, it is suggested that the system is valuable for analyzing structural changes and physiological responses to several regulators in the field of penile medicine.

Experimental study of verapamil on the relaxation of isolated human corpus cavernosum tissues

AIM

To evaluate the relaxant effect of verapamil on human corpus cavernosum in vitro and to assess the drug's potential as a treatment for erectile dysfunction (ED).

METHODS

Preparations of the human corpus cavernosum were obtained from recently deceased young men who had had normal erectile function. The isometric tension and detailed curves were recorded when contractions induced by 10 micromol/L phenylephrine were reduced by different doses of verapamil or the vehicle control (sterile water). The tension of human corpus cavernosum preparations are described as a percentage of their top tension before adding verapamil or the vehicle. ANOVA and least significant difference tests were used for statistical analysis.

RESULTS

Doses of 1 micromol/L, 10 micromol/L and 100 micromol/L verapamil resulted in relaxation of (35.28+/-7.96)%, (55.91+/-6.41)%, (85.68+/-4.16)% after 30 min, respectively. The vehicle control at the same time point produced relaxation of (-0.06+/-10.57)% (P<0.05).

CONCLUSION

Verapamil is significantly effective in relaxing normal human corpus cavernous smooth muscle induced by phenylephrine in vitro and the relaxant effect depends on the concentration of verapamil.

Male sexual function and its disorders: physiology, pathophysiology, clinical investigation, and treatment

This review is designed to help the reproductive endocrinologist integrate his or her professional activity with those of other disciplines including urology, radiology, neurology, and psychology in order to successfully manage all of the inseparable aspects of male sexual and reproductive functioning. Significant advances in the field of male sexual physiology and pathophysiology and new methods of investigation and treatment of male sexual disorders are outlined. The review synthesizes available data on the following: norms of sexual organs, aging and sexuality, role of central and peripheral neurochemicals in each stage of the sexual cycle, role of corporeal smooth muscles in the hemodynamic control of erection and detumescence, influence of psychological factors, drugs, and disease on all aspects of sexual functioning, and use of nocturnal penile tumescence monitoring, imaging investigations, and neurophysiologic studies in the diagnostic workup of males with sexual dysfunction. Clinical algorithms are presented where appropriate. Extensive discussions on newly developed strategies in psychological and behavioral counseling, drug therapy, tissue engineering, nonsurgical devices, and surgical treatments for all forms of sexual disorders are also provided. Lastly, the effect of sexual dysfunction and its treatment on quality of life in affected men is addressed, along with recommendations for future research endeavors.