Androgenic maintenance of inflow and veno-occlusion during erection in therat

Ongoing studies in this laboratory are designed to determine the role of an drogens in the maintenance of the erectile response in the rat. Testosteron e-treated castrated rats (TESTO) and untreated castrated rats (CASTRATE) we re used for measurement of the rate at which blood flows into the cavernous sinuses by timed collections of blood after partial amputation of the peni s. A laser Doppler flow meter was employed to determine whether androgens a lso regulate the veno-occlusive mechanism that controls the rate of blood f low out of the sinuses. Erection was induced by direct electrical stimulati on of the autonomic ganglion that controls cavernosal blood flow in the ere ctile response. The results of these studies showed that blood flow into th e sinuses was approximately twice as great in the TESTO animals as the CAST RATE rats. Furthermore, during ganglionic stimulation, veno-occlusion occur red in the TESTO rats but failed to occur in the CASTRATE rats. The depende nce of these responses on nitric oxide (NO) was demonstrated by showing tha t injection of sodium nitroprusside (SNP) enhances the intracavernosal pres sure response in TESTO rats but not CASTRATE animals. However, when SNP inj ection was combined with ganglionic stimulation, veno-occlusion did occur i n the CASTRATE animals. Taken together, these studies show that both the ra te of blood flow into the cavernous sinuses and the blood flow out are unde r androgenic regulation and may involve the actions of NO.