Impairment of corpus cavernosal smooth muscle relaxation by glycosylated human haemoglobin

OBJECTIVE: To examine the effect of HbA1c, an isoform of glycosylated haemoglobin (GHb, a product of non-enzymatic reactions between elevated blood glucose and haemoglobin), on nitric oxide-mediated corpus cavernosal smooth muscle relaxation, and to categorize the mechanisms involved. MATERIALS AND METHODS: Corpus cavernosal tissue from Wistar rats (300-350 g body weight) was prepared for the measurement of isometric tension. After equilibration in Krebs solution gassed with 95% O2/5% CO2 at 37 degrees C for 90 min, optimal resting tension was applied. Tissue was precontracted with 1 micromol/L noradrenaline (NAd) and either relaxed with incremental doses of acetylcholine (ACh) or sodium nitroprusside (SNP). After washout, strips were again precontracted with NAd and then incubated with pyrogallol (100 micromol/L), 100 microL of haemoglobin or 100 microL of GHb in the presence of either L-arginine (100 micromol/L), indomethacin (10 micromol/L), allopurinol (100 micromol/L), deferoxamine (100 micromol/L), catalase (600 IU/mL), or superoxide dismutase (SOD) (120 IU/mL) before ACh- or SNP-induced relaxation responses were repeated. RESULTS: Haemoglobin and GHb significantly impaired the relaxation of rat corpus cavernosum to ACh in a dose-dependent manner. L-arginine reversed the impairment caused by Hb, but not GHb. A donor of superoxide anions, pyrogallol, mimicked this impairment to ACh when added to control strips. Catalase, deferoxamine, indomethacin and allopurinol had no significant effect on the impaired relaxation response to ACh, whilst L-arginine partially reversed it. SOD completely reversed the GHb-induced impaired relaxation; GHb did not alter the relaxation response to SNP. CONCLUSION: GHb significantly impairs endothelial NO-mediated corpus cavernosal relaxation in the rat, in vitro. This effect is caused partly by the generation of superoxide anions and the extracellular inactivation of NO.     

A patch-clamp study on human sperm Cl- channel reassembled into giant liposome

AIM: To record the single-channel currents and characterize the electrophysiological properties of the Cl- channels in human sperm membrane. METHODS: The membrane proteins extracted from the human sperm were reassembled into liposome bilayer, and the liposomes were fused into giant liposomes with a diameter more than 10 microm by dehydration-rehydration procedure. The giant liposomes were used to study the Cl- channel activities by patch-clamp technique. RESULTS: By patch clamping the giant liposome in an asymmetric NMDG (N-methyl-D-glucamine)-Cl (bath 100// pipette 200 mmol/L) solution system, three kinds of single-channel events with unit conductances of (74.1 +/- 8.3) pS, (117.0 +/- 5.7) pS and (144.7 +/- 4.5) pS, respectively, were detected. Their activities were voltage-dependent and all were blocked by SITS (4-acetamido-4'-isothiocyanato-stilbene-2', 2'-disulfonic acid) in a concentration-dependent manner. By constructing the open and close dwell time distribution histograms and then fitting them with exponential function, two time constants were obtained in both the open and the close states. The burst activity and conductance substate of the channels were observed. CONCLUSION: There exist three kinds of Cl- channels with different conductance in human sperm membrane at least.     

Studies on corpus cavernosal nerve evoked potential in male diabetic rats

Aim: To observe the cavernosal nerve function in male diabetic rats. Methods: Thirty-five male adult SD rats were divided randomly into the diabetic group (n=15) and the control group (n=10). In the diabetic group, diabetes was produced by the administration of streptozotocin (63 mg/kg) at a single intraperitoneal dosing. The latent period of reaction and the corpus cavernosal smooth muscle myopotential were observed after giving a single stimulus to the corpus cavernosal nerve. Results: Compared with the controls, the diabetic rats had a longer latent period and a higher myopotential (both P<0.01). Conclusion: Corpus cavernosal nerve dysfunction may play a role in the erectile dysfunction of diabetic rats.     

Nitric oxide-mediated corpus cavernosal smooth muscle relaxation is impaired in ageing and diabetes

OBJECTIVE: To examine nitric-oxide (NO)-mediated relaxation in cavernosal smooth muscle in a rat model of diabetes, as previous experiments showed that HbA1c (an isoform of glycosylated haemoglobin and a marker of long-term diabetic control) impaired NO-mediated relaxation of normal corpus cavernosal tissue through the generation of superoxide anions. MATERIALS AND METHODS: Eight weeks after the induction of diabetes, male Wistar rats were killed and cavernosal tissue obtained. Strips were contracted with 1 micromol/L noradrenaline before applying acetylcholine or electrical field stimulation (EFS) or sodium nitroprusside (SNP). Relaxation responses were repeated in the presence of L-arginine (100 micromol/L), indomethacin (10 micromol/L) or superoxide dismutase (SOD, 120 IU/mL). Young and age-matched control animals were examined in the same way. RESULTS: Eight weeks of uncontrolled diabetes caused a significant impairment in mean relaxation responses to acetylcholine (P < 0.05) and to EFS (P < 0.05), but not to SNP, compared with young and age-matched controls, respectively. L-arginine, indomethacin and SOD had no significant effect on this impairment. Ageing caused a lesser but significant impairment in EFS-mediated cavernosal smooth muscle relaxation (P < 0.05). CONCLUSION: Diabetes impairs endothelial and neuronal NO-mediated cavernosal smooth muscle relaxation in rats in vitro. This effect is not mediated by an alteration in the intracellular action of NO, the availability of NO, superoxide anion inactivation of NO or the generation of constrictor prostanoids. It is possible that cholesterol or advanced glycation end products are responsible for the effect of diabetes on penile smooth function.     

Separation, culture and identification of SD rat corpus cavernosal endothelial cells

The aim of the study is to investigate the methods of separation, culture and identification of Sprague Dawley (SD) rat corpus cavernosal vascular endothelial cells (CCECs). Cavernosal tissues were isolated from male SD rats. Enzymatic digestion was applied to separate CCECs. Purified cells were obtained using immunomagnetic beads and flow cytometric cell sorting and subcultured in EMG-2 medium. The growth curve of CCECs was measured by the tetrazolium salt 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay. The cells were identified by von Willebrand factor (vWF) using immunofluorescence, and the positive percentage of vWF expression was detected by flow cytometry. The monomorphic cobblestone-like cells were observed by microscopy. High purification was obtained using immunomagnetic beads. After 2 days of incubation, cells entered the logarithmic growth phase and reached a plateau on the fifth day. The vWF expression in cytoplasm was positive. The purity of cells was 95.8%, which was tested by flow cytometry. SD rat CCECs can be separated and cultured successfully by the method of enzymatic digestion, immunomagnetic beads and flow cytometric cell sorting.     

Effect of hypothyroidism on the purinergic responses of corpus cavernosal smooth muscle in rabbits

AIMS: Several studies have reported evidence of hormonal abnormalities in 25-35% of impotent men. Hypothyroidism has been reported to occur in 6% of impotent men. In the present study, we examined purinergic relaxation responses in hypothyroidism in an experimental rabbit model and compared them with controls to evaluate the possible involvement of the purinergic pathway. MATERIALS AND METHODS: The study comprised 20 male New Zealand white rabbits. The rabbits were divided into two equal groups. We tested the effects of ATP, alpha beta ATP, and adenosine precontracted with phenylephrine on the isolated corpus cavernosum preparations from control and hypothyroid rabbits. We also evaluated the effects of ATP, alpha beta ATP, and adenosine on the cGMP levels in the isolated corpus cavernosum preparations from control and hypothyroid rabbits. RESULTS: T(3), T(4), and testosterone levels were significantly lower in hypothyroid rabbits. ATP, alpha beta ATP, carbachol, and electrical field stimulation (EFS)-induced frequency-dependent relaxation responses in the isolated rabbit corpus cavernosum strips precontracted with phenylephrine reduced significantly (P < 0.05). Adenosine-induced relaxation responses did not change significantly in hypothyroid rabbits. CONCLUSION: Reduction of relaxation response in hypothyroid rabbits corpus cavernosum can depend on a decreased release of nitric oxide (NO) from nitrergic nerves and endothelium.     

改良免疫磁珠结合克隆法培养SD大鼠阴茎海绵体内皮细胞

目的:探索大鼠阴茎海绵体内皮细胞(CCECs)分离、纯化和培养的方法,观察其生长特性,并为勃起功能障碍的研究提供种子细胞。方法:采用0.1%弹性蛋白酶消化SD大鼠阴茎海绵体组织,分离原代SD大鼠CCECs,然后采用免疫磁珠纯化,进一步扩增,利用克隆环筛选出单克隆CCECs,并观察其形态及增殖特性,免疫荧光染色鉴定CCECs血管假性血友病因子(VWF)、免疫组化染色鉴定CCECs CD31分子,流式细胞仪测定CCECs纯度,CCK-8法检测CCECs细胞增殖并绘制生长曲线。结果:经克隆环筛选纯化培养1周后倒置相差显微镜下观察到CCECs生长汇合呈铺路石样改变。生长曲线显示CCECs最初1~2 d处于潜伏期,生长缓慢,3~4 d处于对数生长期,生长迅速,第6天进入平台期。免疫荧光染色检测CCECs VWF呈阳性,荧光显微镜下胞质内可见大量绿色荧光。免疫组化检测CCECs CD31分子呈阳性,倒置显微镜下胞质内可见大量黄褐色颗粒。流式细胞仪检测经磁珠联合克隆环纯化VWF标记的CCECs细胞阳性率可达(91.9±3.75)%。结论:免疫磁珠联合克隆环纯化法可成功培养出纯度高SD大鼠CCECs,并可在内皮细胞培养液中稳定生长及传代。     

Dual mechanism of action of nicorandil on rabbit corpus cavernosal smooth muscle tone

The potential of ATP-sensitive potassium channel openers (KCOs) for the treatment of male erectile dysfunction has recently been suggested based on positive clinical outcomes following intra-cavernosal administration of pinacidil. Agents that increase the levels of cGMP via elevation of nitric oxide (NO) nitroglycerin, for example, are also effective in improving erectile function preclinically and clinically. The aim of the present study was to determine the effects and mechanism of the action of nicorandil on rabbit corpus cavernosum. The in vitro regulation of smooth muscle tone was assessed in isolated cavernosal tissues pre-contracted with phenylephrine. Nicorandil, but not its major metabolite, relaxed phenylephrine-precontracted cavernosum smooth muscle with an EC(50) of 15 microM. The effects of nicorandil were only partially reversed by the K(ATP) channel blocker glyburide (10 microM) or by a soluble guanylate cyclase (sGC) inhibitor 1H-[1,2,4] oxadiazole [4,3-a] quinoxalin-1-one (ODQ, 3 microM). However, a combination of ODQ and glyburide completely blocked the relaxant effects of nicorandil. The results of the present study indicate that nicorandil can relax rabbit cavernosal tissue in vitro via a mechanism that involves activation of K(ATP) channels and stimulation of soluble guanylate cyclase.     

Effect of hypothyroidism on the nitrergic relaxant responses of corpus cavernosal smooth muscle in rabbits

BACKGROUND: The incidence of hormonal dysfunction as a cause of impotence remains controversial. However, several recent studies have reported evidence of hormonal abnormalities in 25-35% of impotent men. Hypothyroidism has been reported to occur in 6% of impotent men. METHODS: In the present study, we examined nitrergic responses in hypothyroidism in rabbit corpus cavernosum and compared them with controls. RESULTS: Carbachol-induced relaxation responses and electrical field stimulation (EFS)-induced frequency-dependent relaxations decreased significantly in hypothyroid rabbits. Papaverine and sodium nitroprusside (SNP)-induced relaxation responses did not change significantly in hypothyroid rabbits. The contraction responses of phenylephrine and EFS-induced frequency-dependent contractions were significantly decreased in the hypothyroid group. CONCLUSIONS: We can speculate that the reduction of relaxant responses to EFS and carbachol in hypothyroid rabbits can depend on a decreased release of nitric oxide (NO) from nitrergic nerves and endothelium or a reduction of muscarinic receptor density. Also, decreases in contraction responses may depend on diminished adrenoceptor density.     

Potassium outward currents in freshly dissociated rabbit corpus cavernosum myocytes

PURPOSE: Cavernous smooth muscle cells have a key role in the control of penile erection and detumescence. In this study the types of smooth muscle cells and currents present in isolated rabbit corpus cavernosum myocytes were characterized. MATERIALS AND METHODS: Immunohistochemical methods were used to identify cavernous smooth muscle cells. Currents were recorded from freshly dissociated myocytes using the whole cell and amphotericin perforated patch clamp techniques. RESULTS: Cavernous myocytes were identified by alpha-smooth muscle actin and smooth muscle myosin immunoreactivity. Based on electrical properties at least 2 types of myocytes were present. Type I cells showed more depolarized membrane potentials, lower capacitance, higher input resistance and increased current densities at positive potentials than type II cells. In types I and II cells at voltages positive to 30 mV, maxi K+ channel (Ca2+ activated large conductance K+ channel or BK) blockade with iberiotoxin or charybdotoxin reduced outward currents by approximately 40% to 80% at 80 mV. Maxi K+ channel blocking did not affect cell membrane potential. Type II cells showed delayed rectifier K+ channel-type outward currents that were not detected in type I cells. Delayed rectifier K+ channel-type currents were resistant to iberiotoxin or charybdotoxin, activated at approximately -50 to -40 mV. and inactivated weakly. CONCLUSIONS: The data suggest that cavernous smooth muscle cells are heterogeneous with at least 2 subtypes identified based on membrane potential, capacitance, input resistance, current density and delayed rectifier K+ channel expression. The activation threshold suggests that delayed rectifier K+ channels are open at the resting membrane potential and, therefore, contribute to control and regulation of the cavernous myocyte excitability.     

Effect of chronic renal failure on the purinergic responses of corpus cavernosal smooth muscle in rabbits

OBJECTIVE: To examine purinergic relaxation responses in chronic renal failure (CRF) in an experimental rabbit model, and thus evaluate the possible involvement of the purinergic system in erectile dysfunction with CRF. MATERIALS AND METHODS: The relaxant effects of ATP were measured in strips of corpus cavernosum smooth muscle taken from control and CRF rabbits. CRF was induced in New Zealand white rabbits as previously described. Penises were excised from CRF rabbits 4 weeks after inducing uraemia. In an organ bath the strips from controls and CRF rabbit corpus cavernosum were pre-contracted with phenylephrine and increasing doses of adenosine and ATP added. RESULTS: In the pre-contracted rabbit cavernosal tissue the relaxations induced by adenosine and ATP were unchanged in CRF. CONCLUSION: The lack of any relaxant effect of adenosine or ATP on the relaxation of cavernosal smooth muscle in rabbits with CRF might be because the relaxant effects of these agents are endothelium-independent and the endothelial purinergic receptor density was unchanged in CRF.     

中药益坎胶囊对动脉性勃起功能障碍大鼠阴茎海绵体平滑肌细胞表型转化的影响

目的:探讨中药益坎胶囊对动脉性勃起功能障碍(ED)大鼠阴茎海绵体平滑肌细胞表型转化的影响,以揭示益坎胶囊治疗ED的机制。方法:选取SD大鼠50只,其中10只设为正常组,另40只通过结扎双髂内动脉造成动脉性ED模型。造模后将其中10只设为模型对照组,其余30只灌胃给予ED治疗中药益坎胶囊,浓度分别为1.88、0.94、0.47 g/kg。给药1个月后,经腹腔注射阿朴吗啡,观察大鼠呵欠次数和阴茎勃起次数;切取大鼠的阴茎组织标本,通过免疫组化法观测海绵体平滑肌细胞收缩型性标志物碱性调宁蛋白(calponin 1)和合成型标志物骨桥蛋白(OPN)的表达,实验组结果与正常组和对照组进行比较。结果:注射阿朴吗啡后,正常组大鼠勃起次数为(4.48±1.25)次,模型对照组为(1.63±0.22)次,两组比较,差异有统计学意义(P0.01);给药后,中药益坎胶囊高、中、低剂量组大鼠勃起次数有明显改善[高剂量:(3.05±1.37)次;中剂量:(2.98±0.16)次;低剂量:(1.75±0.40)次]。免疫组化结果显示,模型对照组大鼠海绵体平滑肌细胞calponin 1表达减少,而OPN表达增多,与正常组相比差异有统计学意义(P0.05);与模型对照组相比,给药后,中药益坎胶囊高、中、低剂量组大鼠海绵体平滑肌细胞calponin 1表达增多,OPN表达减少。结论:中药益坎胶囊能改善动脉性ED大鼠的勃起功能,抑制海绵体平滑肌细胞表型由收缩型向合成型转化。     

Effects of Ginkgo biloba extracts with mirodenafil on the relaxation of corpus cavernosal smooth muscle and the potassium channel activity of corporal smooth muscle cells

In this study, we investigated the effects of a combination of Ginkgo biloba extracts (GBE) and phosphodiesterase type 5 (PDE-5) inhibitors on the muscular tone of the corpus cavernosum and potassium channel activity of corporal smooth muscle cells. Strips of corpus cavernosum from male New Zealand white rabbits were mounted in organ baths for isometric tension studies. After contraction with 1×10⁻⁵ mol l⁻¹ norepinephrine, GBE (0.01–1 mg ml⁻¹) and mirodenafil (0.01–100 nmol l⁻¹) were added together into the organ bath. In electrophysiological studies, whole-cell currents were recorded by the conventional patch-clamp technique in cultured smooth muscle cells of the human corpus cavernosum. The corpus cavernosum was relaxed in response to GBE in a dose-dependent manner (from 0.64%±8.35% at 0.01 mg ml⁻¹ to 52.28%±11.42% at 1 mg ml⁻¹). After pre-treatment with 0.03 mg ml⁻¹ of GBE, the relaxant effects of mirodenafil were increased at all concentrations. After tetraethylammonium (TEA) (1 mmol l⁻¹) administration, the increased effects were inhibited (P<0.01). Extracellular administration of GBE increased the whole-cell K⁺ outward currents in a dose-dependent fashion. The increase of the outward current was inhibited by 1 mmol l⁻¹ TEA. These results suggest that GBE could increase the relaxant potency of mirodenafil even at a minimally effective dose. The K⁺ flow through potassium channels might be one of the mechanisms involved in this synergistic relaxation.     

Advanced glycation end-products are responsible for the impairment of corpus cavernosal smooth muscle relaxation seen in diabetes

OBJECTIVE: To determine if advanced glycation end-products (AGEs) are responsible for the lower neuronal and endothelial-derived nitric oxide (NO)-mediated relaxation of corpus cavernosum in tissue in diabetic rats than in control rats. MATERIALS AND METHODS: Diabetes was induced in male Wistar rats by an intraperitoneal injection with streptozotocin (60 mg/kg). One group of diabetic rats was given free access to water and standard diet. A second group was given standard diet and aminoguanidine with their water (50 mg/100 mL) from the initiation of diabetes. Two groups of rats that were not diabetic acted as age-matched controls. After 8 weeks animals were killed by cervical dislocation, corpus cavernosal tissue strips harvested and mounted in an organ bath to measure isometric tension. After 90 min of equilibration at optimal resting tension and contraction with 1 micromol/L noradrenaline, the response to either acetylcholine or electrical field stimulation (EFS) after adding guanethidine (5 micromol/L) and atropine (1 micromol/L) was determined for each group. RESULTS: There was no difference between the baseline characteristics of all the experimental groups. After 8 weeks the mean body mass and glycosylated haemoglobin (HbA1c) were significantly greater in the diabetic than in control animals. Aminoguanidine had no effect on the recorded body mass or HbA1c. The in vitro relaxation response to the application of acetylcholine or EFS of tissue strips from age-matched control animals fed a standard diet and those supplemented with aminoguanidine were the same. The administration of aminoguanidine to diabetic animals for 8 weeks reversed the expected impaired relaxation response to acetylcholine; the response to EFS was similar. CONCLUSION: AGEs are more prevalent in erectile tissue from diabetic than in control animals. Aminoguanidine reversed the impairment in neuronal and endothelial NO-mediated penile smooth muscle relaxation seen in diabetes. As aminoguanidine prevents AGE formation, erectile dysfunction in diabetes is probably caused partly by the generation of AGEs.     

The effect of DA-8159 on corpus cavernosal smooth muscle relaxation and penile erection in diabetic rabbits

A previous study showed that DA-8159, a potent type 5 phosphodiesterase inhibitor, enhanced the relaxation of the smooth muscles in the normal rabbit corpus cavernosum. In this study, we investigated the in vitro effects of DA-8159 on cavernosal smooth muscle relaxation and the in vivo erectogenic potential in diabetic rabbits, since erectile dysfunction is a well-known sequela of diabetes mellitus. Diabetes mellitus was induced in male New Zealand White rabbits with alloxan monohydrate. Cavernosal strips from age-matched control and 8-week diabetic animals were mounted in organ baths. The relaxation responses to sodium nitroprusside (10^-910^-5 M), a nitric oxide donor, were assessed in the presence or absence of DA-8159 (10^-910^-6 M). For the penile erection test, DA-8159 was given orally (1~10 mg/kg) to diabetic rabbits and the length of the uncovered penile shaft was measured in a time-course manner in the presence or absence of intravenous sodium nitroprusside. The sodium nitroprusside-stimulated relaxations were significantly impaired in the corpus cavernosum from the diabetic group (IC₅₀=1.07×10^-6 M following 8 weeks of diabetes mellitus; compared with 0.48×10^-6 M for age-matched controls). DA-8159 significantly and dose-dependently enhanced the sodium nitroprusside-stimulated relaxation in the diabetic groups. In addition, DA-8159 induced a dose-dependent penile erection in diabetic rabbits, which was potentiated by intravenous sodium nitroprusside. These results suggest that DA-8159 is an effective treatment for diabetic erectile dysfunction but further evaluation of the efficacy on human needs to be performed.     

Cl- channels in basolateral TAL membranes. XIV. Kinetic properties of a basolateral MTAL Cl- channel

BACKGROUND: This article reports studies on the kinetics of chloride (Cl-) conductance in Cl- channels fused into bilayers from basolaterally enriched vesicles from rabbit outer medulla. A considerable body of evidence indicates that these channels represent rbClC-Ka, a 77 kDa kidney-specific protein of the ClC family of Cl- channels. rbClC-Ka, a candidate channel for mediating net Cl- absorption in the medullary thick ascending limb (MTAL), has been cloned from rabbit outer medulla and localized by immunofluorescence to basolateral membranes of the MTAL. Thus, this is the first account, to our knowledge, of the kinetics of ion permeation through a renal Cl- channel mediating net basolateral Cl- absorption in the thick ascending limb of Henle (TALH), and this channel may represent rbClC-Ka. METHODS: The electrophysiological properties of these channels were studied by fusing basolaterally enriched MTAL vesicles into planar bilayer membranes. RESULTS: Cl- conductance through these channels was concentration dependent and saturable. The relationship between gCl (pS) and symmetrical aqueous Cl- concentrations could be expressed in terms of the Michaelis equation with a limiting conductance (GClmax, pS) of 114 pS at infinitely high aqueous Cl- concentrations and a K1/2 of 163 mM Cl-. A log-log plot of the conductance-Cl- concentration relations, in the nonsaturating Cl- concentration range, had a slope of 0.91, that is, virtually unity. The relatively impermeant anion I- produced a voltage-dependent conductance blockade that could be overcome at high electric field strengths. CONCLUSIONS: The experimental data described earlier here fulfill the traditional criteria for a first-order process with a single Cl- ion occupying these channels at a given time. Although the channels may contain multiple ion binding sites, the latter function, in integral kinetic terms, as a single rate-limiting locus.     

Phentolamine relaxes human corpus cavernosum by a nonadrenergic mechanism activating ATP-sensitive K+ channel

To investigate the pharmacodynamics of phentolamine in human corpus cavernosum (HCC) with special attention to the role of the K+ channels. Strips of HCC precontracted with nonadrenergic stimuli and kept in isometric organ bath immersed in a modified Krebs-Henseleit solution enriched with guanethidine and indomethacine were used in order to study the mechanism of the phentolamine-induced relaxation. Phentolamine caused relaxation (approximately 50%) in HCC strips precontracted with K+ 40 mM. This effect was not blocked by tetrodotoxin (1 microM) (54.6+/-4.6 vs 48.9+/-6.4%) or (atropine (10 microM) (52.7+/-6.5 vs 58.6+/-5.6%). However, this relaxation was significantly attenuated by L-NAME (100 microM) (59.7+/-5.8 vs 27.8+/-7.1%; P<0.05; n = 8) and ODQ (100 microM) (62.7+/-5.1 vs 26.8+/-3.9%; P<0.05; n = 8). Charybdotoxin and apamin (K(Ca)-channel blockers) did not affect the phentolamine relaxations (54.6+/-4.6 vs 59.3+/-5.2%). Glibenclamide (100 microM), an inhibitor of K(ATP)-channel, caused a significant inhibition (56.7+/-6.3 vs 11.3+/-2.3%; P<0.05; n = 8) of the phentolamine-induced relaxation. In addition, the association of glibenclamide and L-NAME almost abolished the phentolamine-mediated relaxation (54.6+/-5.6 vs 5.7+/-1.4%; P<0.05; n = 8). The results suggest that phentolamine relaxes HCC by a nonadrenergic-noncholinergic mechanism dependent on nitric oxide synthase activity and activation of K(ATP)-channel.     

Virtual cavernoscopy: a novel diagnostic tool for use in the corpus cavernosal lumen in patients with erectile dysfunction

Study Type – Diagnostic (case series) Level of Evidence 4 What’s known on the subject? and What does the study add? In visualizing the artery in patients with ED, digital subtraction angiography, CT angiography and color Doppler ultrasonography has been performed. There were difficulties with the previous methods in visualizing the stenotic lesion, or parts beyond the obstruction of the artery. Virtual cavernoscopy can visualize an artery independently of blood flow. We therefore believe that this new imaging technology will contribute to better ED practice.

OBJECTIVE

? To evaluate virtual cavernoscopy as a diagnostic tool in erectile dysfunction.

PATIENTS AND METHODS

? Forty patients who visited our hospital for investigation of erectile dysfunction underwent cavernosography using three‐dimensional (3D)‐computed tomography (CT). ? Virtual cavernoscopic images were reconstructed from 3D‐CT data.

RESULTS

? Virtual cavernoscopic images were obtained from all patients. ? Virtual cavernoscopy visualized the corpus cavernosal lumen surrounded by the tunica albuginea, the septum of the cavernosum, the outlets of the veins, and cavernous arteries. ? The visualization of each structure depended on the window level (WL). At WL 400, the virtual cavernoscopy visualized only a fibrous structure. At this WL, the internal view of the corpus cavernosum was expressed as a hollow space. At WL 1600, the virtual cavernoscopy visualized the cavernous artery as a filling defect. ? Out of 80 lumens in the 40 subjects, arteries in 14 lumens were detected by both virtual cavernoscopy and CT angiography, while arteries in 50 lumens were detected only by virtual cavernoscopy. Arteries in two lumens could not be visualized by either method and those in 14 lumens were visualized only by CT angiography.

CONCLUSION

? In visualizing the artery, conventional imaging techniques depend on blood flow, whereas using virtual cavernoscopy an artery can be visualized independently of blood flow. Virtual cavernoscopy is unique in this regard and we therefore believe that this new imaging technology will contribute to better ED practice.