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Objectives: The Ras homolog gene family, member A (RhoA) and its main downstream effector, Rho-kinase (ROCK) are important in maintaining the penis in the flaccid state. The pathophysiology of sickle cell disease-associated priapism is not well defined. We hypothesized that the RhoA/ROCK vasoconstrictive pathways might be involved in the development of priapism. Therefore, the objective of the present study was to evaluate the molecular changes in RhoA and ROCK in an established transgenic sickle cell mouse model of priapism., Methods: Two groups of mice were used: wild type (WT; C57BL/6) mice and transgenic sickle cell mice. We evaluated RhoA guanosine triphosphatase and total ROCK activities, as well as ROCK1 and ROCK2 protein expression, in WT and sickle mice penises. We also evaluated the in vivo erectile responses to cavernous nerve stimulation and the frequency and duration of spontaneous erections before and after cavernous nerve stimulation., Results: Sickle mice demonstrated significantly (P <.05) enhanced erectile responses to cavernous nerve stimulation and frequency of spontaneous erections both before and after cavernous nerve stimulation compared with the WT mice. The sickle mice penises had a significant decline in RhoA guanosine triphosphatase (P <.01) and total ROCK activities (P <.05) compared with the WT mice. A significant (P <.05) reduction in ROCK2 protein expression in sickle mice penises compared with WT mice protein expression. No change in ROCK1 protein expression was observed in either cohort of mice penises., Conclusions: These data suggest that sickle cell disease associated-priapism might be contributed by a lack of RhoA/ROCK-mediated vasoconstriction and highlight a novel molecular mechanism in the pathophysiology of priapism., (Copyright 2010 Elsevier Inc. All rights reserved.)

Objectives: To evaluate the effect of the fibrin sealant, Evicel, on the neuroregulatory control of penile erections in an experimental rat model., Methods: Two groups of rats were used: sham-operated rats with exposure of the bilateral cavernous nerves (CNs) and application of saline vehicle (500 microL), and rats treated with direct application of Evicel (500 microL) bilaterally to the CNs. At 14 and 45 days after application of Evicel to the CNs, the CNs were stimulated to measure the in vivo erectile responses. Additionally, we evaluated the neuronal nitric oxide synthase immunoreactivity in the dorsal CNs of the penis and changes in the smooth muscle and collagen deposition in the penis using a trichrome stain., Results: Evicel application to the CNs did not have any detrimental effect on the neurogenic erectile responses in vivo at 14 or 45 days after application. The neuronal nitric oxide synthase expression in the dorsal CNs of the penis was unchanged after Evicel application at all points studied, and we saw no change in the histomorphometric analysis findings of smooth muscle and collagen deposition in the penis., Conclusion: These data suggest that the hemostatic agent, Evicel, is safe in an experimental rat model of erection physiology, with no detrimental effects on neuroregulatory control of erection.