Corpus cavernosum electromyography: could it be a parameter to predict ageing?

In this study, we investigated whether electromyography of corpus cavernosum (CC-EMG) results vary with age and whether CC-EMG could be a parameter to predict ageing of cavernous smooth muscle. Recordings of electrical activity of corpus cavernosum (EACC) were retrospectively investigated in 134 patients with erectile dysfunction. Penile colour Doppler ultrasonography and cavernosometry were also performed for all of the patients. The total number and duration of EACC and amplitudes between positive and negative peaks were compared between the flask state for 10 min and after intracavernosal papaverine injection. The mean age of the 47 patients in group 1 was 35.2 ± 6.3 years (range, 23-44), the mean age of the 45 patients in group 2 was 51.1 ± 3.1 years (range, 45-56) and the mean age of the 42 patients in group 3 was 61.8 ± 4.6 years (range, 57-77). Total IIEF-5 score was 7.6 ± 2.1 in group 1, 7.9 ± 2.4 in group 2 and 7.9 ± 2.1 in group 3. There were no statistically significant differences among the groups regarding electrical potential frequencies, durations and amplitudes of electromyographic recordings. Conclusion: We do not think that CC-EMG findings could be used efficiently as a predictor of ageing.     

衰老对大鼠阴茎勃起机制的影响

为探讨衰老对阴茎勃起机制的影响程度,以不同月龄的雄性大鼠分别观察海绵体神经诱导的阴茎勃起,海绵体平滑肌的舒张功能以及阴茎含ＮＯＳ神经和平滑肌量。结果表明电刺激老年鼠海绵体神经可取得与年轻和中年鼠相当的勃起压力,但勃起潜伏期较长。注射罂粟碱提示老年海绵体平滑肌顺应性较年轻鼠差。检查还提示老年鼠阴茎内含ＮＯＳ神经和平滑肌纤维量有一定减少。实验证实衰老对阴茎勃起机制中关键性的组织结果和功能有一定影响,但     

盆神经节海绵体内移植对双侧海绵体神经损伤后大鼠阴茎勃起功能的影响

目的　研究双侧海绵体神经离断后 ,自体盆神经节海绵体内移植对大鼠阴茎勃起功能的影响。方法　将 2 6只雄性SD大鼠 (3～ 6个月 ,30 0～ 4 0 0g 只 )随机分为 2组 :(1)实验组 (n =16 )行双侧海绵体神经离断及左盆神经节移植入左侧阴茎脚内 ;(2 )对照组 (n =10 )仅离断双侧海绵体神经。1个月及 3个月后阿朴吗啡皮下注射检测勃起功能 ,电刺激左阴茎脚移植区域或右侧盆神经节比较海绵体内压的变化 ,NADPH染色检测海绵体内一氧化氮合酶 (NOS)阳性神经纤维 ,透射电镜观察盆神经节移植后的存活情况。结果　两组大鼠 1个月及 3个月后注射阿朴吗啡后均无勃起反应 ;电刺激左阴茎脚盆神经节移植区域后亦不能导致勃起。 1个月后电刺激两组左阴茎脚后的海绵体内压变化分别为 (9 4 1± 3 2 0 )、(4 16± 2 5 8)cmH2 O(t=4 76 9,P <0 0 5 ) ,3个月后分别为 (13 6 7± 4 18)、(5 0 9± 2 74 )cmH2 O(t=9 18,P <0 0 5 )。两组大鼠左阴茎脚区域的NOS阳性神经纤维数目 1个月后分别为 (2 18 7± 2 4 5 )、(18 0± 3 7) (t=14 77,P <0 0 5 ) ,3个月后分别为 (183 2± 19 7)、(19 0± 3 8) (t =12 18,P <0 0 5 ) ;透射电镜证实了神经节移植后的存活。结论　盆神经节海绵体内移植后可以存     

电刺激阴茎背神经和海绵体内注射药物诱导大鼠阴茎海绵体内压反应

目的:评价阴茎海绵体内压(ICP)监测在电刺激阴茎背神经和海绵体内注射罂粟碱诱导大鼠阴茎勃起反应中的应用。方法:选取性成熟雄性SD大鼠8只,20%氨基甲酸己酯(1000mg/kg)腹腔注射麻醉下,暴露阴茎并解剖阴茎背神经(DN),将充满肝素盐水并连接于压力传感器的25G针头插入一侧海绵体,取另一30G头皮针插入对侧海绵体,分别用于测定ICP和注射血管活性药物。分别以电刺激海绵体神经(刺激参数:电压4V,波幅0.5ms,频率16Hz,持续20s)和海绵体内注射罂粟碱(0.4mg)诱发阴茎勃起,采用SMUPPC型生物信号处理系统记录ICP变化。结果:麻醉大鼠的ICP基线水平为(12.3±3.1)mmHg(1mmHg=0.133kPa),DN电刺激后约30～60sICP明显升高[(36.4±2.3)mmHg,P<0.05],电刺激结束后缓慢下降至基线水平。海绵体内注射罂粟碱后5～8min可诱发ICP明显升高[(28.4±6.1)mmHg,P<0.05]。结论:监测电刺激大鼠DN及海绵体内药物注射诱发的ICP,为阴茎勃起这一复杂神经血管活动的动物模型在体实验研究提供了一种客观准确的科学工具,对于进一步研究阴茎勃起生理和勃起功能障碍的发病机制,评价治疗勃起功能障碍新疗法的疗效等具有重要意义。     

Evaluation of the role of corpus cavernosum electromyography as a noninvasive diagnostic tool in male erectile dysfunction

Corpus cavernosum electromyography (EMG) and its evolution: single potential analysis of cavernous electrical activity (SPACE) seem to be promising diagnostic methods in the evaluation of erectile dysfunction and smooth muscle integrity [4]. Our study concentrates on the role of EMG in the evaluation of corpus cavernosum smooth muscles, using it as a noninvasive technique for demonstrating autonomic erectile dysfunction through their influence on recording SPACE and consequent proper selection of patients for different therapeutic modalities. A total of 80 male patients were examined for the feasibility of transcutaneous registration of cavernous electrical activity with a 2-channel electrophysiological unit (Evamatic 2000, Dantec) with two surface electrodes bilaterally placed on the penile shaft. Ten patients had normal erectile function, but complained of other urological symptoms. They served as the controls for normal electrical activity. Fifty patients with organic impotence of nonvascular (neurogenic) or vascular (venogenic, arteriogenic) aetiologies were subjected to EMG in both the flaccid and the erect state. On the basis of the EMG patterns the patients were divided into the following groups: 34 patients having normal tracing in both the flaccid and the erect state, and 21 patients showing abnormal patterns of waves with evidence of autonomic neurogenic dysfunction and incomplete smooth muscle relaxation. Of the latter 4 had long-standing diabetes mellitus and 4 had spinal injuries.     

Comparative Study between Corpus Cavernosum-Electromyography Findings and Electron Microscopy of Cavernosal Muscle Biopsies in Erectile Dysfunction Patients

Background: Biopsy and electrical activity recordings of the corpus cavernosum are 2 new diagnostic methods for the evaluation of impotent men. We evaluated the corpus cavernosum ultrastructure and electromyography (EMG) recordings from patients with erectile dysfunction.
Methods: Twenty erectile dysfunction patients with veno-occlusive dysfunction underwent a detailed history, physical examination, biochemical tests, hormonal analysis, injection of an intracavernous vasoactive agent (60 mg papaverine-HCI), color penile Doppler ultrasonography, cavernosometry/ cavernosography and corpus cavernosum electromyography (CC-EMG). Thirteen patients underwent total vein ligation and 7 had penile prosthesis implantations. Tissue samples were obtained during surgery from both corpora cavernosa and examined by transmission electron microscopy. Control corporal tissue samples were taken from 3 cadavers.
Results: In 15 patients, CC-EMG recordings were 15.6 ± 0.65 μV in the flaccid state, which decreased in 13 patients after papaverine (5.61 ± 0.25 μV; P < 0.001). Five patients with diabetes mellitus had low amplitudes in the flaccid state (5.26 ± 0.45 μV), which did not vary significantly after a papaverine injection (4.99 |pL 0.75 μV). The pathology of the corpus cavernosum biopsy specimens revealed a smooth muscle cell thickened basal membrane, dilated rough endoplasmic reticulum, and increased numbers of fibroblasts, but ultrastructurally normal endothelial cells lining the and sinusoids. There was no difference between samples from diabetic or nondiabetic patients, or from either side of the corpora cavernosa. The only pathologic change observed in the controls was mitochondrial swelling.
Conclusion: CC-EMG is less invasive and a valuable method in patients with erectile dysfunction, whereas no specific findings were observed from penile biopsy specimens.     

In vivo and in vitro investigation of the effects of sildenafil on rat cavernous smooth muscle

PURPOSE: We investigated the effect of sildenafil on rat erectile tissues in vivo and in vitro. MATERIALS AND METHODS: Intracavernous pressure was recorded in pentobarbital anesthetized, male Sprague-Dawley rats and we studied the effect of 100 or 200 microg/kg(-1) sildenafil given intravenously. In an isolated endothelin-1 contracted strip preparation of rat corpus cavernosum we also assessed the effect of sildenafil on the response to electrical field stimulation of the nerves. RESULTS: Electrical stimulation of the cavernous nerve induced a frequency dependent increase in intracavernous pressure of a mean plus or minus standard error of mean 55 +/- 3 mm Hg at 20 Hz, corresponding to a mean of 47% +/- 2% of mean arterial pressure. The 100 microg/kg(-1) dose did not increase intracavernous pressure but significantly increased mean decay time of the pressure response from 16 +/- 3 to 35 +/- 3 seconds (p <0.001). In vitro sildenafil significantly enhanced the amplitude and duration of the relaxation induced by the electrical stimulation of corpus cavernosum strips in a concentration dependent fashion. CONCLUSIONS: In anesthestized rats sildenafil significantly prolonged the decay period of the intracavernous pressure response induced by electrical stimulation of the cavernous nerve but it did not increase the amplitude. Sildenafil enhanced the amplitude and duration of the relaxant response to electrical field stimulation in isolated corpus cavernosum tissue.     

Effects of transanal pelvic plexus stimulation on penile erection: clinical implications

Objective To determine the ability of transanal pelvic plexus stimulation (TPPS) in inducing penile tumescence in patients with non-neurogenic erectile dysfunction (ED) and to compare the erection degree with papaverine-induced erection. Patients and methods The cavernous electrical activity (CEA) in 21 men with non-neurogenic erectile dysfunction was measured during TPPS by electromyography of corpus cavernosum and the erection degree of penis (flaccid, semi-rigid, rigid) was noted. The stimulation amplitude was increased from 20 to 100 mA. All patients also underwent intracavernous papaverine injection and further CEA recordings were obtained. Results Twelve and nine patients were diagnosed with vasculogenic (VED) and non-vasculogenic ED (NVED), respectively. TPSS led to a penile erectile response in 12 patients (57%), whereas papaverine injection caused erection in 16 (76.2%) patients. The mean baseline CEA (16.9 ± 9.1 mV) did not change with TPPS, but papaverine significantly decreased the mean CEA to 12.3 ± 4.9 mV (P < 0.001). CEA recordings of 16 (76.2%) patients revealed a significant decrease after papaverine injection, however seven (33.3%) patients showed significant CEA decrease in response to TPPS. Both TPPS and papaverine were observed to have a higher effect in patients with NVED in terms of inducing penile erection and decreasing CEA compared to their effects in patients with VED. Conclusion TPPS induces penile erection and decreases CEA for some extent, but to a lesser degree compared to papaverine. As further improvements are achieved in the methodology of TPPS, it may be a valuable method in the evaluation patients with erectile dysfunction.     

Electromyographic Changes of Corpus Cavernosum Due to Papaverine and Nitroprusside in Veno-Occlusive Dysfunction

Purpose

We compared electrical activity of the corpus cavernosum after intracavernous papaverine and nitroprusside injections. Some aspects of the androgen modulator system in patients with veno-occlusive dysfunction are discussed.

Materials and Methods

Electromyography of the corpus cavernosum was performed before and 1 day after intracavernous injection of 60 mg. papaverine and 400 microgram sodium nitroprusside in 22 patients with veno-occlusive dysfunction. Changes in duration and amplitude of electromyographic potentials were compared in groups with and without incoordination patterns.

Results

The decreases in electrical amplitude and duration in 15 patients with a negative incoordination pattern, and increases in 7 with a positive pattern were more significant with intracavernous sodium nitroprusside than with papaverine injections.

Conclusions

Electromyographic changes were more prominent with nitroprusside than with papaverine, which demonstrates the use of nitroprusside when performing corpus cavernosum electromyography.     

Standardized evaluation of erectile dysfunction in 95 consecutive patients

We investigated 95 patients referred for erectile dysfunction by penile blood pressure measurement, the intracavernous papaverine test and Doppler investigation of the penile arteries. Furthermore, penile cutaneous perception threshold, bulbocavernosus reflex latency and somatosensory cortical evoked potentials of the pudendal nerve were measured. In selected cases cavernosometry, cavernosography and corpus cavernosum electromyography were performed. Doppler investigation of the cavernous arteries after papaverine injection was more reliable than penile blood pressure measurement in the diagnosis of arteriogenic erectile dysfunction. Decreased sensibility of the penis may be the sole factor responsible for inability to sustain an erection. Erectile dysfunction may be provoked by impaired function of the pudendal nerve. Penile cutaneous perception threshold measurement and corpus cavernosum electromyography are mandatory in the evaluation of neurogenic etiology. Cavernosometry and cavernosography are reliable methods in the determination of abnormal drainage from the corpus cavernosum.     

Evaluation of a no-needle penile injector: a preliminary study evaluating tissue penetration and its hemodynamic consequences in the rat

Objectives

Intracavernous needle injection is an effective delivery method for pharmacotherapy of erectile dysfunction. Needle phobia, pain, and concern about local tissue injury have stimulated the search for new, less invasive means of inducing penile erection. In this preliminary communication, we evaluate a jet injector as an alternative to needle injection for intracavernous delivery of vasoactive drugs.

Methods

Jet injection was evaluated in three groups of rats receiving either India ink, saline, or papaverine into the penis. The ability of the jet injection to penetrate through the tunica albuginea and deliver liquid to the corpora cavernosa smooth muscle was assessed by the degree of staining within the corpus cavernosum (ink group), histologic change (saline group), and rise in intracavernous pressure (papaverine group). Erectile capacity following cavernous nerve electric stimulation was compared before and 1 hour after injection of saline or papaverine.

Results

Ink traversed the skin and tunica albuginea with extensive deposition noted within the cavernous spaces. Varying degrees of subcutaneous hemorrhage were seen with saline jet injection; however, the corpus cavernous smooth muscles showed no evidence of injury. Jet injection of papaverine 3250 gmg significantly increased cavernous pressure (39.4 ± 4.6 cm H₂O) compared with saline injection (2.8 ± 1.3 cm H₂O).

Conclusions

We conclude that acute jet injection is an effective method for intracavernous delivery of drugs. Long-term effects should be evaluated prior to clinical use.     

Morphological changes in penile vessels during erection: the mechanism of obstruction of arteries and veins at the tunica albuginea in dog corpora cavernosa

The present study deals with morphological changes during erection both in the penile deep artery supplying the corpus cavernosum and in veins draining it. These vessels were shown to maintain wide lumina in the flaccid state. In the erect state induced by injection of papaverine, the postcavernous venules were compressed between the cavernous sinuses and the tunica albuginea. Simultaneously, the penile deep artery and the penetrating vein were strangulated by stretched collagen bundles in the inner layer of the tunica albuginea. Quite noteworthy was a wedge-shaped connective tissue mass between the penetrating vein and the postcavernous venules converging to it, and plugged, in the erect state, towards the penetrating vein to effectively stem the venous outflow. When the rigid state was induced by papaverine injection and following intracavernous injection of a fixative by high pressure, the arterial and venous obliteration mentioned above was so intense that the vessels almost lost their lumina, resulting in the cavernous sinuses becoming isolated from the systemic circulation.     

Intracavernosal pressure monitoring in mice: responses to electrical stimulation of the cavernous nerve and to intracavernosal drug administration

With the development of transgenic mice to evaluate mechanisms of erectile function, it appears particularly advantageous to develop a standardized mouse model of penile erection. The purpose of the study reported here was to evaluate the novel application of intracavernosal pressure (ICP) monitoring in the mouse during electrophysiologic and pharmacologic induction of penile erection. In anesthetized adult male mice, the cavernous nerves (CN) were isolated unilaterally, and the corpora cavernosa were exposed. A 24-gauge angiocath (intravenous catheter) was inserted into the right corpus cavernosum to monitor the ICP, and a 30.5-gauge needle was inserted into the left corpus cavernosum for intracavernosal drug administration. ICP was recorded during CN-stimulated or pharmacostimulated erections. Electrical stimulation of the CN significantly increased the ICP (from 10.09 +/- 2.01 to 34.62 +/- 2.71 mm Hg, P < .05), which then returned to baseline pressure after termination of the electrical stimulation. Pretreatment with intracavernosal administration of the nitric oxide synthase inhibitor, nitro-L-arginine methyl ester (0.1 mg), inhibited the electrical stimulation-induced changes in ICP (7.17 +/- 1.46 vs 10.38 +/- 2.17 mm Hg, not significant [NS]). Also, intracavernosal administration of papaverine (0.4 mg) produced a significant increase in ICP (from 8.51 +/- 0.69 to 26.37 +/- 5.7 mm Hg, P < .05). We concluded that this technique might be applied to perform quantitative erection physiologic experiments with the mouse as an economical and experimentally advantageous animal model, particularly with the development of transgenic mice to evaluate mechanisms of erectile function.     

Fibrosis of corpus cavernosum in animals following cavernous nerve ablation

Aim: To investigate alterations of smooth muscle celis and collagen fibers in corpus cavernosum following cavernous neurectomy and its relation to the expression of transforming growth factor-β1 (TGF-β1). Methods: Ten adult male SD rats (neurectomy group) were subject to a bilateral cavernous nerve (CN) resection aseptically under an operating microscope, with 6 sham-operated rats as the control. Fifteen weeks after the operation, the penile speci mens were collected and prepared for quantitative-analyzing of ratio of smooth muscle to collagen fibers in corpus cavernosum with confocal microscopy, and for detecting the expression of TGF-β1 by RT-PCR and western-blot. Resulte: Smooth muscle celis that show red color after fluorescent-labeling with tetramethylrhodamine isothiocyanate phalloidin and collagen fibers that produce green autofluorescence after paraformaldehyde fixation were clearly iden tified     

Electromyographic changes after deep dorsal vein arterialization

PURPOSE: To investigate the cavernosal electromyographic changes after deep dorsal vein arterialization. PATIENTS AND METHODS: Corpus cavernosum electromyographs (CC-EMG) were done in 18 patients with patent anastomosis 1 year after the operation by using coaxial needle electrodes during the flaccid state and following intracavernous 60 mg papaverine injection. RESULTS: The mean preoperative amplitude and relaxation degree measurements were found to be 77 +/- 11 microV and 34 +/- 8%, respectively. The same recordings 1 year after the operation were 140 +/- 24 microV and 76 +/- 11%, respectively. Comparisons of preoperative and postoperative values revealed statistically significant results (p < 0.0001). CONCLUSION: Smooth muscle restoration of cavernous tissue was proved by observing the postoperative increases in the amplitude and relaxation degree parameters of CC-EMG.     

Regeneration of neuronal nitric oxide synthase (nNOS)-containing nerve fibers in rat corpus cavernosum

Aim: To investigate the effect of cavernous nerve injury on the nNOS-containing nerve fibers in rat corpus cavernosum.Methods: Thirty-three male SD rats were randomized into 3 groups: 5 rats underwent pelvic exploration without tran-section of cavernous nerve as the sham-operated controls, the unilateral injury group (14 rats) had the cavernous nerve cuton one side, and the bilateral injury group (14 rats) had the nerves cut on both sides. Corpora cavernosa were harvestedat the 3rd week and 6th month after surgery, nNOS-positive nerve fibers were examined with strepavidin peroxidase im-munohistochemistry techniques (SP method). Results: After bilateral ablation, the nNOS-positive nerve fibers weresignificantly decreased at both the 3rd week ( 17 ± 4) and the 6th month (16 ± 4). For the unilateral injury group, thenNOS-positive nerve fibers were similarly decreased on the side of the neurotomy at the 3rd week (18 ± 6), but by the 6thmonth, the number increased significantly (61±9) and approximated th     

The meanings of the papaverine test

Intracavernous administration of papaverine is now commonly employed for diagnosis and therapy of impotence. To assess the pharmacokinetics of papaverine, we recorded its concentration in peripheral blood and also in cavernous blood after intravenous and intracavernous injection of 40 mg of papaverine. Peripheral blood was sampled serially after injection. Plasma was immediately extracted and then kept at at -40 degrees C until analysis. High pressure liquid chromatography was used to record the concentration of papaverine. The maximum serum concentration of papaverine measured after intracavernous injection was 7.7 ng/ml, which was considerably lower than the average serum concentration of 24.0 ng/ml after intravenous injection. Peak serum concentration was reached 1 min after intravenous injection and 10 min after intracavernous injection. It is clear that the corpus cavernosum constitutes a separate pharmacokinetic compartment. Therefore there was no significant difference between the papaverine concentration in peripheral blood of patients who showed full erection after intracavernous injection and that of patients who did not achieve erection. The concentration of papaverine in the intracavernous blood of a fully erected penis was only about 1 microgram/ml after 20 min. This concentration is similar to that in cavernous blood of those who showed excessively persistent erection. Our results imply that papaverine administered into the cavernous space relaxes smooth muscle, and is then washed out to general circulation, and the concentration in the cavernous space reaches a low level of about 1 microgram/ml. The low concentration level is maintained for several hours during erection. Therefore, we presume that papaverine acts on both the inflow system and smooth muscle of cavernous tissue in the phase of producing erections.(ABSTRACT TRUNCATED AT 250 WORDS)     

The hypoactive corpora cavernosa with degenerative erectile dysfunction: a new syndrome

Background

In a group of 22 patients with erectile dysfunction, vasculogenic, neurogenic, endocrinologic or psychogenic investigations failed to find a cause for their erectile dysfunction. The electro-cavernosograms of these patients recorded a diminished activity. We investigated the hypothesis that diminished corpus cavernosum electromyography activity was the cause of erectile dysfunction in these patients.

Methods

The study comprised the above mentioned 22 patients (study group, 43.8 ± 5.9 SD years) and 15 healthy volunteers (control group, 41.8 ± 5.1 SD years). The electro-cavernosograms were recorded in the flaccid, erectile and detumescent phases by 2 electrodes inserted into the corpus cavernosum.

Results

The electro-cavernosogram of the healthy volunteers registered in the flaccid phase regular slow waves and random action potentials. The wave variables declined significantly in the erectile phase (p < 0.01). In the study group, the slow wave variables in the flaccid phase exhibited a significant decrease (p < 0.05) compared to the healthy volunteers, and the rhythm was irregular. Erection did not occur with sildenafil administration or intracavernosal papaverine injection, and penile implant was performed. Biopsy examination showed degenerated muscle fibers, and fragmented collagen and elastic fibers with areas of fibrosis.

Conclusion

A novel concept of the cause of erectile dysfunction was presented. Corpora cavernosa showed degenerative changes on histopathologic examination and exhibited diminished electromyography activity. They did not respond to sildenafil administration or intracavernosal papaverine injection. Penile implants were the only treatment. The condition is given the name 'hypoactive corpus cavernosum'. The cause of corpus cavernosum degenerative changes needs further study.     

Effect of intraurethral papaverine on penile erection in rats

OBJECTIVES: The aim of this study is to investigate erectile response to intraurethral administration of papaverine in rats. MATERIAL AND METHODS: Male Sprague-Dawley rats were used in this study. Under urethane anesthesia, penis was exposed and intracavernous pressure (ICP) was recorded through a 23-gauge needle, which was inserted into right corpus cavernosum. Effects of intraurethral application of incremental doses of 0.2 ml papaverine gel (4-17.5 mg) on intracavernosal pressure were observed and compared with those of 0.4 mg papaverine applied into corpus cavernosum. Mean arterial blood pressure (MABP) and heart rate were also monitored. RESULTS: The mean basal ICP was 8.9 +/- 1.8 mm Hg. Intraurethral administration of papaverine did not increase ICP at any doses used in this study. After intracavernous injection of papaverine (0.4 mg), a significant increase in the ICP occurred from resting (8.9 +/- 1.8 mm Hg) to a peak at 57.5 +/- 9.9 mm Hg and persisted for 22.3 +/- 6.7 minutes (p < 0.05). The latter application significantly decreased MABP (22.3 +/- 3.1 mm Hg; p < 0.05). CONCLUSIONS: Intraurethral administration of papaverine does not seem to be an alternative to other erectile dysfunction treatment modalities. However, further studies on animals are necessary at higher concentrations or in combination with other mucosal enhancers to increase the effect of intraurethral administration of papaverine.     

Cavernous and systemic testosterone levels in different phases of human penile erection

OBJECTIVES: To examine changes in testosterone levels in the cavernous and peripheral blood during different phases of erection because, although the determination of systemic testosterone levels has been well established in the diagnostic workup of erectile dysfunction, the exact role of testosterone in adult male sexual function remains unclear. METHODS: Blood samples were drawn simultaneously from the corpus cavernosum and the cubital vein of 54 healthy and normally potent volunteers during four different stages of the cavernous erectile tissue (flaccidity, tumescence, rigidity, and detumescence). Penile erections were induced by audiovisual and tactile stimulation, and testosterone levels were determined by radioimmunoassay. RESULTS: The mean testosterone level in the corpus cavernosum plasma during the flaccid state was 2.9 +/- 1.2 ng/mL. During tumescence and rigidity, the testosterone levels in the cavernous blood significantly increased, to 4.3 +/- 1.3 ng/mL and 4. 4 +/- 1.4 ng/mL, respectively. During detumescence, the cavernous testosterone levels dropped to 3.5 +/- 1.4 ng/mL. The changes in the testosterone levels in the peripheral plasma were less pronounced. A significant increase was also found in the peripheral testosterone levels from flaccidity (4.1 +/- 1.1 ng/mL) to tumescence (4.4 +/- 1. 4 ng/mL). No further increase in testosterone occurred during the phase of rigidity. From rigidity to detumescence, the peripheral testosterone levels dropped to 4.1 +/- 1.2 ng/mL. CONCLUSIONS: Penile erection was found to be accompanied by a significant increase in cavernous and systemic testosterone plasma levels. The estimated difference between the systemic and cavernous testosterone levels during penile flaccidity, when blood flow through the cavernous body is minimized, might be a diagnostic tool to evaluate the amount of bioavailable testosterone and the activity of testosterone receptors in the corpus cavernosum smooth musculature.