Hemodynamics of the canine penis during erection

To elucidate the change of hemodynamics of the penis during erection induced by neurostimulation to the pelvic nerve, we measured the blood flow rates (BFR) through the dorsal penile artery and vein (DPA and DPV), and the internal pudendal artery (IPA) with the intracavernosal and intraspongiosal pressures (ICP and ISP). After DPA were ligated bilaterally, we compared BFR through DPV and ICP with those before ligations. In addition, PVO2 within DPV was determined. When neurostimulation was switched on, BFR through IPA and DPA began to increase. But during erection, BFR through IPA was lower than the flow in the tumescence phase, although the BFR through DPA remained unchanged. Then ISP elevated. When the full erection was achieved, the pressure remained above the prestimulation level, although a gradual decrease in the pressure was observed. On the other hand, ICP dropped transiently for 5 to 10 seconds, and then increased rapidly. BFR through DPV increased rapidly, which coincided with the transient drop in ICP. As soon as neurostimulation was switched off, BFR through IPA, DPA, DPV and ISP decreased to the base line, although ICP still remained elevated. The BFR through DPV and ICP were compared before and after ligation of bilateral DPA. BFR through DPV decreased after ligation during the non-erectile period, but no significant changes were found during the erectile period. ICP did not change significantly after ligation in either period. PVO2 within DPV was higher than that in the internal iliac vein and peripheral vein during both non-erectile and erectile period. In the erectile period, it rose up to a level near that within the aorta.(ABSTRACT TRUNCATED AT 250 WORDS)     

Endothelial nitric oxide synthase keeps erection regulatory function balance in the penis

OBJECTIVES: We evaluated the regulatory influence of endothelial nitric oxide (NO) on the basal functional states of the NO and RhoA/Rho-kinase signaling pathways in the penis using endothelial NO synthase (eNOS) mutant mice and eNOS gene transfer technology. METHODS: Four groups of mice were used: wild type (WT), eNOS gene deleted (eNOS-/-), eNOS and neuronal NOS gene deleted (dNOS-/-), and eNOS-/- mutant mice transfected intracavernosally with eNOS. Cyclic guanosine monophosphate (cGMP) concentration, protein kinase G (PKG) activity, activated RhoA, and Rho-kinase activity were determined in penes of WT and both mutant mouse groups. Constitutive NOS and PKG activities, RhoA, Rho-kinase-alpha and -beta isoforms, and phosphorylated myosin light-chain phosphatase target subunit (p-MYPT-1) expressions and Rho-kinase activity were determined in penes of eNOS-/- mice after eNOS gene transfer. RESULTS: Compared with results in the WT penis, eNOS-/- and dNOS-/- mutant mouse penes had significant reductions in NOS activity, cGMP concentration, PKG activity, Rho-kinase activity, and p-MYPT-1 expression (p<0.05) with no significant changes in activated RhoA or in RhoA and Rho-kinase-alpha and -beta protein expressions. After eNOS gene transfer to penes of eNOS-/- mice, Rho-kinase-beta and p-MYPT-1 expressions and total Rho-kinase activity were significantly increased from baseline levels (p<0.05). CONCLUSIONS: These data suggest that endothelial NO has a role in the penis as a regulator of the basal signaling functions of the NO and RhoA/Rho-kinase erection mediatory pathways. These data offer new insight into the homeostasis of erection regulatory biology.     

Electrical activity of corpus cavernosum during flaccidity and erection of the human penis: a new diagnostic method?

We investigated 7 normal men and 1 diabetic patient with erectile dysfunction. Electromyography electrodes were placed in the corpus cavernosum of the penis and electrical activity was recorded during flaccidity. With sexual arousal the activity decreased and tumescence was initiated. During tumescence and full erection the electrical activity of the corpus cavernosum almost ceased but in the diabetic patient (neurogenic impotence) an increase was observed. This discoordination might be the cause of the erectile dysfunction. Recording the electrical activity of the corpus cavernosum in patients with suspected neurogenic erectile dysfunction could become clinically valuable, since this is the first test possible to study the function of the autonomic motor system that normally regulates penile function.     

The hemodynamics of erection at the level of the penis and its local deterioration

We have studied penile structure in 300 specimens from cadavers, 3,000 patients undergoing general physical examination and more than 700 patients operated on for organic impotence. Special attention has been focused on the closure mechanism of the corpora cavernosa during erection. Venous outlets of the corpora cavernosa normally are situated only on the distal third of the ventral penile surface. A firm, lasting erection requires a tight albuginea of the corpora cavernosa, with perfect closure of the venous outlets. During life use of the penis or, eventually, misuse by repeated long-lasting, firm erections (high pressure in the corpora cavernosa) results in deterioration of the tightness of the albuginea, especially when the albuginea is thin (25 per cent of the cases). We have found that a leakage factor of the corpora cavernosa is the most frequent cause of organic impotence in aging men.     

TVP中出现闭孔神经和阴茎勃起反射的原因分析

探讨经尿道前列腺电气化术中出现闭孔神经和阴茎勃起反射的有关问题。方法：采用ＴＶＰ治疗前列腺增生症１５６例。结果术中分别出现闭孔神经反射和阴茎勃起反 和７例,均发生于气化电极接近神经分支和气化电流较强时。     

Dimensions, volume and rigidity of the penis. Fundamental elements in the study of the erection and its dysfunctions

The length and the proximal and distal circumferences of the flaccid and erect penis were measured as part of the aetiological investigation of 62 impotent patients. These measurements, compared with the quantitative study of penile rigidity, demonstrate the lack of correlation between circumference changes and rigidity and constitute a simple method for the measurement of penile volume variations and, when compared with penile rigidity, provide important information concerning the physiology of erection and its dysfunction.     

Prevention of erection after penile surgery

Summary To prevent noctural erections after penile surgery a randomized, double blind trial of nocturnal intracavernous infusion of noradrenaline (10 micrograms per hour) versus placebo in 20 patients was carried out. During infusion the corpus cavernosum pressure was continuously registered. The patients made a record of nocturnal erections and associated pain. The pressure registration confirmed total absence of erections in the noradrenaline group. In the placebo group half of the patients were devoid of nocturnal erections. No signs of ischaemia was seen, but in four patients receiving noradrenaline infusion was stopped due to pain. This treatment seems effective in preventing nocturnal erections after penile surgery.     

Opacification of the glans penis during cavernosography

Cavernosography and cavernometry were performed in 150 impotent patients and 10 normal potent volunteers. Opacification of the glans penis was noted in 5 normal volunteers, while among the impotent patients it was noted in 53 per cent of those with venous leakage and in 36 per cent of those without leakage. We believe that opacification of the glans during cavernosography must be regarded as a normal variant rather than as a sign of pathological shunts between the glans and the corpora cavernosa.     

Feline penile erection induced by topical glans penis application of combination alprostadil and SEPA (Topiglan)

The objective of this study was to evaluate the efficacy of topically applied prostaglandin E1 (PGE(1))+5% SEPA (soft enhancement of percutaneous absorption) on the glans penis in a feline erection model. Erectile response after glans penis administration of PGE(1)+5% SEPA cream (Topiglan, MacroChem Co., Lexington, MA, USA) was compared to the erectile response after intracavernosal administration of the triple-drug combination (1.65 mg papaverine, 25 microg phentolamine, and 0.5 microg PGE(1)). The placebo cream and increasing concentrations (0.25%, 2.5 mg/ml; 0.5%, 5 mg/ml; and 1%, 10 mg/ml) of PGE(1)+5% SEPA were applied in a total volume of 0.1 ml via a plastic needle-less syringe. The control triple-drug combination was administrated intracavernosally via a 30-gauge needle at the completion of each experiment to serve as a control reference. With each application of placebo, PGE(1)+SEPA, and the triple-drug combination, changes in intracavernosal pressure and systemic blood pressure were continuously monitored. Topical application of PGE(1)+SEPA induced increases in intracavernosal pressure in a dose-dependent manner, with minimal effects on systemic blood pressure. The increases obtained with 1% PGE(1) Topiglan cream were similar to the intracavernosal pressure values elicited by the standard intracavernosal triple-drug combination. These data demonstrate that topical glans penis application of PGE(1)+SEPA can induce an erectile response in cats with minimal systemic adverse effects. Oral pharmacological agents are the first-line treatment for male ED. Studies investigating the effectiveness of noninvasive modalities such as topical therapy should continue, because these agents have the potential to avoid the systemic effects commonly seen with oral therapies. Additionally, topical therapy may also benefit patients who are unresponsive to oral agents or have explicit contraindications. Topical PGE(1) application to the glans penis may become an important treatment option in selected patients suffering from erectile dysfunction.     

Entrapment of the median nerve after dislocation of the elbow

Entrapment of the median nerve as a complication of a dislocation of the elbow has rarely been reported. The prognosis is worse in case of delayed diagnosis. Exploration surgery is indicated when neurological signs remain following reduction of a dislocation of the elbow.     

Hemodynamics of canine corpora cavernosa during erection

Being able to induce erection by electrical stimulation of the cavernous nerves, we studied the hemodynamics of canine penile erection. Simultaneous recording of flow and pressure of the internal pudendal artery as well as pressure within the corpus cavernosum clearly demonstrated that increase of arterial flow preceded corporeal pressure increase. When saline was infused directly into the corpus cavernosum, with the aorta clamped, decreasing venous flow during erection could be demonstrated. Tumescence of the corpus cavernosum was found to be a result of active relaxation of sinusoidal spaces, active arteriolar dilatation, and active venous constriction. At full erection, there was still flow into and out of the corpus cavernosum, although it was reduced to only a fraction of a milliliter per minute.     

Protective role of the glans penis during coitus

To examine the hypothesis that the glans penis acts protectively, absorbing forces, during coitus. Five potent patients (mean age 46.8+/-9.7 y), who had indication for surgical excision of the glans for penile carcinoma were included in the present study. Intraoperatively, intracavernosal pressure (ICP) was adjusted by saline infusion and maintained by a pressure feedback infusion pump to a pressure value of 70 mmHg. Using a dynamometer, an external compressive force of 0.5 kg was applied at the glans penis and the changes in ICP were monitored. Measurements were repeated after surgical excision of the glans. Significant ICP changes were noticed in all patients after excision of the glans. Mean preoperative ICP was 161+/-11.5 mmHg, while after glansectomy it reached 206.6+/-13 mmHg. DeltaICP was 45.8+/-10.57 mmHg. Two of the patients' partners reported pain during intercourse postoperatively, possibly due to the impact of the force applied by the rigid corpora cavernosa on the anterior vaginal wall without any absorption by the glans. The glans penis restricts the increase in ICP during sexual intercourse, playing a protective role for both the corpora cavernosa and the female genitalia.     

Autonomic control and vascular changes during penile erection in monkeys

The mean pressure in the unstimulated corpus cavernosum of monkeys was 12.1 mm Hg. Pelvic nerve stimulation at 8 to 10 Hz produced penile extension and the mean pressure increased to 64.3 mm Hg (47-84% of carotid artery pressure) after a latency of 10 s. On stopping stimulation, recovery to resting levels occurred within 2 min. The response was not blocked by atropine or propranolol. Blood flow through two 19 gauge needles inserted into the corpus cavernosum increased in parallel with the pressure changes, indicating that arterial inflow increased. Stimulation of either hypogastric nerves or the sympathetic chain produced penile retraction but increased corpus cavernosal pressure. The response to pelvic nerve stimulation was partially blocked. It was concluded that both of these nerves contract penile erectile tissue within the corpus cavernosum and constrict arterial inflow.     

Entrapment of the median nerve after posterior dislocation of the elbow

The authors present two cases of complete median nerve paralysis due to entrapment after posterior dislocation of the elbow. Previous literature on the subject matter is reviewed, and management and therapeutic indication of these lesions are discussed.     

Repeated PGE1 treatment enhances nitric oxide and erection responses to nerve stimulation in the rat penis by upregulating constitutive NOS isoforms

PURPOSE: To assess whether intracavernosal injections of prostaglandin E1 (PGE1) can influence nitric oxide (NO) release in the corpora in a rat model of penile erection. MATERIALS AND METHODS: The extracellular levels of NO were monitored at 100 seconds intervals in the corpus cavernosum of anesthetized rats by using differential normal pulse voltammetry with porphyrin-Nafion coated carbon fiber microelectrodes. The intracavernosal pressure (ICP) was simultaneously recorded. PGE1 was given either as a single dose (ranging from 0.2 to 15 microg.) or as repeated 2 microg. injections in alternate days for two weeks. The NO and ICP responses to electrostimulation of the cavernosal nerve (SCN) was studied in the animals in the repeated treatment schedule at 1, 7, 15 and 30 days after its termination. The levels of the three NO synthase (NOS) isoforms in the cavernous tissue were measured by immunoblotting. RESULTS: Acute PGE1 treatment dose-relatedly increased NO levels in the corpora, with a concomitant ICP increase with the highest dose. Repeated 2 microg. PGE1 injections increased the NO and ICP responses to SCN as compared with intact or vehicle-injected animals. This treatment also increased the penile content of the neuronal and endothelial NOS proteins. The inducible NOS isoform remained unchanged after either vehicle or PGE1 injections. The effects of the repeated PGE1 treatment were greater in the group studied 24 hours after the last injection and decreased progressively thereafter. CONCLUSIONS: Stimulation of NO release can contribute to the erectogenic effect of intracavernous PGE1 injections. The increased levels of constitutive NOS isoforms in the corpora could contribute to the improvement of the erectile function reported by some patients following repeated treatment with vasorelaxant agents.     

Further evidence of venous outflow restriction during erection

To elucidate the effect of venous outflow restriction during erection, we studied eight dogs during artificial saline perfusion of the penis with and without neurostimulation to induce erection. With the infrarenal aorta clamped temporarily, saline infusion rates of 0.9 and 1.9 ml/min raised the mean intracorporeal pressure to 34 and 42 cm H2O, respectively, before stabilisation or return to baseline. When cavernous nerve stimulation was initiated, the mean intracorporeal pressure rose to 124 and 184 cm H2O (with infusion rates of 0.9 and 1.9 ml/min respectively) to induce full erection. Our results show that venous outflow restriction takes place during erection and that it is necessary not only to induce full erection but also to maintain it. Evaluation of venous competence is therefore essential during the investigation of impotence.     

Effects of castration and testosterone replacement on veno-occlusion during penile erection in the rat

AIM: To determine if androgens directly regulate veno-occlusion or if androgens act indirectly to maintain the penile structures which control outflow. METHODS: Using CASTRATE and TESTO rats, measurement was made of mean arterial pressure (MAP), intracavernosal pressure (CCP), and intracavernosal flow (CCF) during erection resulting from stimulation of the autonomic innervation of the penis. CCP and CCF were also measured during saline infusion into the cavernosal sinuses before and after treatment with sodium nitroprusside (SNP, a nitric oxide donor drug) to fully relax cavernosal smooth muscle. Penile tissue was also collected to measure the content of alpha actin and proline and hydroxyproline to determine if brief withdrawal of androgenic support led to changes in the number of smooth muscle cells or the collagen content of the tissue. RESULTS: Infusion of saline into the cavernosal sinuses demonstrated that veno-occlusion was defective in CASTRATE rats while veno-occlusion was fully functional in TESTO animals. Furthermore, veno-occlusion could be induced in CASTRATE rats if they were first treated with SNP. This observation suggests that failure of veno-occlusion in the CASTRATE rats is due to a deficiency in the production of NO resulting in a reduction in the degree of relaxation of the penile smooth muscle. The measurements of smooth muscle a actin and proline and hydroxyproline content of collagen showed that both were unaffected by castration and that the basic structure of the penis did not degenerate after one week without androgenic support. CONCLUSION: These results can be interpreted to mean that androgens control the veno-occlusive mechanism indirectly via a NO dependent mechanism and not by maintaining the structures of the penis which are essential to veno-occlusion.