人激肽释放酶对离体动物阴茎海绵体平滑肌的舒张效应

目的探讨人组织激肽释放酶对离体动物阴茎海绵体平滑肌的舒张效应,以初步探讨其对阴茎勃起的调节作用。方法通过离体阴茎海绵体平滑肌肌条实验方法,利用PowerLab4SP微弱生物信号采集系统记录人组织激肽释放酶对离体家兔和大鼠阴茎海绵体平滑肌的舒张效应。结果100mU人组织激肽释放酶可分别使去氧肾上腺素诱导的家兔和大鼠阴茎海绵体平滑肌舒张(65.98±6.98)%和(54.86±9.65)%。结论人组织激肽释放酶可强力地舒张离体家兔和大鼠阴茎海绵体平滑肌,推测其对人阴茎海绵体平滑肌也会有较强的舒张效应,可能是勃起功能障碍药物开发的一个新靶点。     

Nitric oxide mediates relaxation in rabbit and human corpus cavernosum smooth muscle

Summary We investigated in vitro the relaxant effect of exogenous acetylcholine (ACh) and electric-field stimulation (EFS) on rabbit and human corpus cavernosum smooth muscle strips (CC) precontracted with phenylephrine. The effects of EFS and ACh were monitored alone, after muscarinic receptor blockade and after inhibition of nitric oxide (NO) formation with l-N-nitroarginine (l-NOARG). In rabbit und human CC, both atropine and l-NOARG abolished the relaxant effects of ACh. The relaxant effects of EFS, however, were only slightly reduced by atropine to 97.5±17.5% in human CC and to 89.0±6.1% in rabbit CC. l-NOARG further reduced the EFS effects to 0.8±1.7% in human CC and to 16.2±8.7% in rabbit CC. In strips obtained from impotent patients with diabetes mellitus, the relaxant effects appeared to be significantly less than in strips from nondiabetic impotent men. Tetrodotoxin blocked the relaxant EFS effects in human and rabbit strips completely. The data indicate the important role of NO in cholinergically induced relaxation of cavernous smooth muscle in rabbits and humans. Our findings support the idea of NO as the nonadrenergic noncholinergic neurotransmitter in penile erection in both species. Rabbit erectile tissue might serve as an in vitro animal model for further investigation.     

Relaxation mechanisms of neferine on the rabbit corpus cavernosum tissue in vitro

Aim： To investigate the relaxation mechanisms of neferine （Nef） on the rabbit corpus cavemosum tissue in vitro. Methods： Strips of rabbit corpus cavemosum were mounted in organ chambers. The effects of Nef were examined on isolated muscle strips precontracted with phenylephrine （PE） alone, in the presence of NW-nitro-L-arginine （LNNA, a nitric oxide synthase inhibitor）, 1-H-[ 1,2,4]oxadiazolo[4,3-tx]quinoxalin- 1-one （ODQ, a guanylyl cyclase inhibitor）, indomethacin （cyclooxygenase inhibitor）, tetraethylammonium （Ca^2＋ -activated K^＋ channel blocker）, 4-aminopiridine （4-AP ,voltage dependent K^＋ channel blocker） and glibenclamide （ATP sensitive K^＋channel blocker）. The effects of Nef on KCl-induced contraction of isolated muscle strips were also investigated. The procedure of calcium absencecalcium addition was designed to observe the effect of Nef on two components of the contractile responses to PE based on the source of Ca^2＋ （extracellular vs. intracellular）. Results： Corpus cavemosum strips relaxed in response to Nef （10-9-10-4 mol/L） in a concentration-dependent manner with an IC50 of 4.60 × 10^-6 mol/L. However, they were not affected by LNNA, ODQ, indomethacin or K^＋-channel blockers. Nef （10^-6 mol/L, 10^-5 mol/L） concentration dependently reduced the maximal contraction response of isolated strips induced by KC1 to 79.3% ± 5.5% and 61.5% ±3.2%, respectively （P 〈 0.01）. In the calcium absence-calcium addition procedure, Nef 10.5 mol/L inhibited both intracellular calcium-dependent and extracellular calcium-dependent contraction induced by PE （2 × 10^5 mol/L） （P 〈 0.05）. The inhibition ratios were 26.2% ± 5.4% and 48.3% ±7.6%, respectively. Conclusion： The results of the present study suggest that Nef possesses a relaxant effect on rabbit corpus cavemosum tissues, which is attributable to the inhibition of extracellular Ca^2＋ influx and the inhibition of release of intracellular stored Ca^2＋, but not mediated by the     

维拉帕米对离体家兔阴茎海绵体平滑肌舒张作用的实验研究

目的　初步探讨维拉帕米 (VP)对离体兔阴茎海绵体平滑肌的舒张作用及其机制。方法　离体家兔阴茎海绵体平滑肌条实验方法 ,观察VP对阴茎海绵体平滑肌的舒张效应。结果　VP可舒张去氧肾上腺素 (PE)诱导的阴茎海绵体平滑肌收缩作用 ,最大舒张效应为 (4 6 .3± 2 .1) % (P <0 .0 1) ,且呈浓度依赖性。 10 -6mol·L-1,10 -5mol·L-1和 10 -4mol·L-1VP均可使PE引起的浓度 -效应曲线右移 ,最大收缩反应降低 ,10 -4mol·L-1VP拮抗作用更显著。结论　VP有明显的舒张阴茎海绵体平滑肌作用 ,并呈浓度依赖性。     

阴茎包埋对海绵体结构和发育的影响

目的探讨阴茎包埋对海绵体结构和发育的影响。方法通过建立隐匿阴茎动物模型获得实验标本，分2个月组、4个月组和6个月组进行观测。检测海绵体质量和大鼠体重，观察发育情况；Masson染色分析海绵体内平滑肌和纤维结缔组织的含量来了解海绵体结构的变化。结果各阶段包埋组动物阴茎海绵体质量、体重及两者的比值与正常组和假手术组两两比较差异均无统计学意义（P〉0．05）；各阶段中包埋组的海绵体平滑肌面积下降（2个月组P〉0．05，4个月和6个月组P〈0．05），纤维结缔组织面积增加（2个月和4个月组P〉0．05，6个月组P〈0．05）血管窦的面积减少（2个月和4个月组P〉0．05，6个月组P〈0．05），且组织的正常形态发生改变。结论阴茎包埋可影响海绵体内平滑肌和纤维结缔组织的含量及组织排列的正常形态，且与包埋时间正相关，但对海绵体的大体观无明显影响。     

阴茎包埋对海绵体内勃起通路的影响

目的 观察阴茎包埋对海绵体内勃起通路的影响.方法 通过建立大鼠隐匿阴茎模型获得实验标本,分2、4、6个月组进行观测.各阶段中包括包埋组、假手术组和正常组.采用紫外分光光度计检测海绵体内一氧化氮合酶(NOS)的活性,免疫组织化学法显示雄激素受体(AR)在海绵体内的表达水平.结果 3个时间段内包埋组NOS活性分别为1.79、1.67、1.24 U/mg·prot,与正常组和对照组比较,酶活性降低随包埋时间延长逐渐显著(2个月组P>0.05,4个月组P<0.05,6个月组P<0.01),但包埋对各阶段大鼠阴茎海绵体内AR表达水平无影响.结论 阴茎包埋可直接影响勃起通路中最重要的神经递质一氧化氮合成的关键酶-NOS的活性来影响勃起通路,且这种影响与阴茎包埋时间正相关.     

Relaxant effects of some benzothiazolinone derivatives on isolated rabbit corpus cavernosum

 In the present study, two 6-(fluorobenzoyl)-3-piperazinomethyl-2-benzothiazolinone derivatives were synthesized and their relaxant effects on isolated rabbit corpus cavernosum investigated. Compounds Y-16 and Y-21 can alter the ability of corpus cavernosum smooth muscle to contract. Strips of rabbit corpus cavernosum smooth muscle were mounted in isolated tissue baths for measurement of isometric contractile force. Compounds (10⁻⁶–10⁻³ M) did not cause contraction but induced relaxation in precontracted corpus cavernosum smooth muscle. Neither N-nitro-l-arginine methylester (L-NAME) nor indomethacin affected the relaxant effect of these compounds. Glibenclamide and tetraethylammonium chloride (TEA) also did not influence the relaxation induced by the compounds. In conclusion, in isolated rabbit corpus cavenosum, Y16 and Y21 have a relaxant potency equal or superior to known vasoactive agents. Further investigations are needed to show the importance of these effects for the diagnosis and treatment of erectile dysfunction. Received: 5 December 2000 / Accepted: 5 March 2001     

血红素氧合酶在糖尿病大鼠阴茎海绵体的表达

目的 检测血红素氧合酶1和2( HO-1/HO-2)在糖尿病(DM)大鼠阴茎海绵体(CC)的表达变化,探讨其在糖尿病相关勃起功能中的作用.方法 SD雄性大鼠50只,随机取30只制作糖尿病模型,余20只为正常对照.4周和8周后用阿扑吗啡试验评价大鼠勃起功能;免疫组织化学法及Western blot法检测HO-1、HO-2在大鼠CC内的表达部位及水平.结果 DM大鼠勃起次数在4周(2.17±0.94)和8周(0.85±1.07)时与对照组[4.0±1.15(4周);4.2±1.32(8周)]比均下降(P＜0.01),HO-1在4周(32.87±3.22)和8周(20.65±2.34)时的表达高于相应对照组[13.52±3.25(4周);12.35±2.29(8周)],P＜0.01,但8周较4周表达降低(P＜0.01),HO-2在4周(14.32±1.21)和8周(8.82±2.35)时的表达均低于相应对照组[20.91±2.07(4周);21.02±2.10(8周)],P＜0.01,且随时间逐渐加重(P＜0.01);对照组间差异无统计学意义(P＞0.05).结论 糖尿病造成大鼠勃起功能下降,可能与HO在DM大鼠CC内的表达降低密切相关.     

Apoptosis of corpus cavernosum in patients with organic erectile dysfunction

Objectives  It has been reported that apoptosis of penile erectile tissue occurs after penile denervation, castration, and diabetes mellitus in animal studies. Aim of this study was to investigate apoptosis in corpora cavernosa of patients with organic erectile dysfunction (ED). Methods  Cavernous biopsies were obtained from 38 patients with erectile dysfunction and 10 patients with normal erectile function. Apoptosis of tissues were determined via terminal deoxyuridine nucleotide end labeling method by using flow cytometry. Results  The mean ages of patients with ED and control patients were 50.65 ± 2.27, and 32.43 ± 2.90 years, respectively (P = 0.0001). Patients with ED were set in two groups as more than 50 years old and less than 50 years old for further analysis of age factor on apoptosis. The mean % apoptosis of ED patients was 26.22 ± 2.79 and control group was 11.26 ± 3.79, (P = 0.032). Mean fluorescence intensity (MFI) values were also 17.41 ± 3.21 and 6.59 ± 2.28, respectively (P = 0.039). MFI and % apoptosis values were not statistically significant different neither between the patients groups nor between the control and patients ≤50 years old (P > 0.05). Conclusions  We did not find any statistically significant difference with respect to apoptosis rates when we compared neither control group with ≤50 years old patients nor patients groups of ED. Because of this we did not have enough data to say that apoptosis has a prominent role on the development of ED independently from other factors. However, further studies are necessary to clarify the role of apoptosis in erectile dysfunction.     

Quantitative functional outcomes of the conservative management of partial segmental thrombosis of the corpus cavernosum

The low incidence of partial segmental thrombosis of the corpus cavernosum (PSTCC) means its management is guided by isolated case reports. Erectile function is an important outcome that has not been described quantitatively in the literature. We present two cases of PSTCC managed conservatively. Although both patients reported resolution of local symptoms, formal analysis of sexual function at follow-up review has revealed that only one achieved complete recovery.     

Long-term results of corpus cavernosum autoinjection therapy for chronic erectile dysfunction

Between May 1985 and March 1992, 172 patients suffering from chronic erectile dysfunction (21-70 years old) underwent constant corpus cavernosum autoinjection therapy (CAT) with a standardized papaverine phentolamine mixture (16385 injections). Thereafter 41 patients continued CAT with the single agent papaverine (1257 injections). On the basis of both these 17642 protocol auto-injections, and over 6 years of experience with intracavernosal autoinjection therapy we conclude that, especially with the papaverine-phentolamine mixture, CAT constitutes an effective therapy (full rigidity in 95.8%) with tolerable side-effects for chronic erectile dysfunction when preceded by careful patient selection and thorough multi-disciplinary evaluation. This is especially so in the case of arterial and/or neurogenic aetiology of the erectile dysfunction. In addition, the contraindications must be strictly observed, the treatment and technique fully explained, and a regular follow-up instituted. CAT is generally well accepted by the patients and their partners (98.8%/97.6%) and has distinct positive effects on self-esteem (77.8%), performance anxiety (84.4%), and partnership (79.5%). The most serious side-effect was prolonged erection (25 out of 17642 injections). In 6 patients reversible fibrotic changes near the tunica albuginea were observed.     

Lack of effect of carbon monoxide inhibitor on relaxation induced by electrical field stimulation in corpus cavernosum

Carbon monoxide has been proposed as a possible neurotransmitter because of its ability to bind to the iron atom of the heme of guanylyl cyclase, which is similar to that of nitric oxide. To determine whether carbon monoxide exerts an effect on the penis, strips of rabbit corpus cavernosum were mounted in an organ bath for isometric tension studies and the effect of zinc deuteroporphyrin, an inhibitor of heme oxygenase which metabolizes hemoprotein and releases carbon monoxide, on relaxation induced by electrical field stimulation (neurally mediated) was determined. Also observed was relaxation induced by electrical field stimulation after incubation with atropine and guanethidine to isolate nonadrenergic noncholinergic neurotransmission. Zinc deuteroporphyrin (10^-6M, 10^-5M, 10^-4M and 3x10^-4M) did not affect relaxation induced by electrical field stimulation in the absence or presence of guanethidine and atropine. Therefore, it appears that carbon monoxide does not contribute to neurally mediated relaxation of the rabbit corpus cavernosum.     

Ex vivo relaxation effect of Cuscuta chinensis extract on rabbit corpus cavernosum

The effect of Cuscuta chinensis extract on the rabbit penile corpus cavernosum (PCC) was evaluated in the present study. Penises obtained from healthy male New Zealand white rabbits (2.5–3.0 kg) were precontracted with phenylephrine (Phe, 10 µmol l⁻¹) and then treated with various concentrations of Cuscuta chinensis extract (1, 2, 3, 4 and 5 mg ml⁻¹). The change in penile tension was recorded, and cyclic nucleotides in the PCC were measured by radioimmunoassay (RIA). The interaction between Cuscuta chinensis and sildenafil was also evaluated. The result indicated that the PCC relaxation induced by Cuscuta chinensis extract was concentration-dependent. Pre-treatment with an nitric oxide synthase (NOS) inhibitor (Nω nitro-L-arginine-methyl ester, L-NAME), a guanylyl cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, ODQ), or a protein kinase A inhibitor (KT 5720) did not completely inhibit the relaxation. Incubation of penile cavernous tissue with the Cuscuta chinensis extract significantly increased cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) in the PCC. Moreover, the Cuscuta chinensis extract significantly enhanced sildenafil-induced PCC relaxation. In conclusion, the Cuscuta chinensis extract exerts a relaxing effect on penile cavernous tissue in part by activating the NO-cGMP pathway, and it may improve erectile dysfunction (ED), which does not completely respond to sildenafil citrate.     

Relaxation effects of adrenomedullin in isolated rabbit corpus cavernosum smooth muscle

OBJECTIVES: To clarify the pharmacological effects of adrenomedullin, a potent vasodilator and hypotensive peptide isolated from human phaeochromocytoma cells, on corpus cavernosal smooth muscle in vitro, as the intracavernosal injection of adrenomedullin induces penile erection in the anaesthetized cat. MATERIALS AND METHODS: The effects of adrenomedullin were investigated in isolated muscle strips from New Zealand rabbit corpus cavernosum smooth muscle pre-contracted with phenylephrine alone, in the presence of indomethacin (cyclooxygenase inhibitor), Nomega-nitro l-arginine methyl ester (L-NAME, a nitric oxide synthase inhibitor), and K+-channel blockers. RESULTS: Adrenomedullin caused relaxation of isolated pre-contracted rabbit corpus cavernosum strips in a concentration-dependent manner. The response of corpus cavernosum was unaffected L-NAME, indomethacin and K+-channel blockers. CONCLUSION: The relaxation exerted by adrenomedullin in rabbit corporal tissue may arise from the effect of the drug on its specific receptors and/or calcitonin gene-related peptide-1 receptors. The relaxant effect of adrenomedullin might lead to novel clinical applications for erectile dysfunction.     

Tolerance to isosorbide dinitrate in isolated strips of rabbit corpus cavernosum

The aim of this study was to investigate whether prolonged exposure to a high concentration of isosorbide dinitrate (ISDN) would result in tolerance being developed against its relaxant activity in strips of corpus cavernosum, pre-contracted by phenylephrine. Under these conditions, relaxation induced by ISDN was found to be significantly reduced. Strips made tolerant to ISDN remained fully responsive to sodium nitroprusside and papaverine. Electrical field stimulation evoked relaxations which were persistent in the presence of tolerance-inducing conditions. These results indicate that desensitization of guanylate cyclase activity is not likely to be the operating mechanism for nitrate tolerance. We suggest that tolerance may result from the impairment of biotransformation of ISDN in rabbit cavernosal smooth muscle.     

Effect of magnesium on the function of the rabbit corpus cavernosum

Contraction and relaxation of the smooth muscle, including the corpus cavernosum, are mediated by changes in the intracellular concentration of calcium. Since magnesium modulates the movement of calcium it can modify the function of the erectile tissue. We designed this study to investigate the effects of magnesium in doses ranging from 5 to 30 mM on the function of the rabbit corpus cavernosum in vitro. The resting tension of tissue strips was significantly reduced by exposure to a solution high in magnesium (5–30 mM). The contractile response to field stimulation under resting conditions, and the contraction to phenylephrine, were significantly decreased by magnesium (5–30 mM). There were no differences in the contractile strength of the corpus cavernosum to KCl. Although the relaxation induced by field stimulation under preincubation with 200 M phenylephrine was abolished in the presence of 30 mM magnesium, there were no differences at a concentration of 5 mM or of 10 mM magnesium. The relaxation induced by sodium nitroprusside under precontraction with 200 M phenylephrine was further increased by magnesium dose dependently. A high concentration of magnesium (30 mM) enhanced both bethanechol-induced and ATP-induced relaxations under precontraction with phenylephrine. Our study demonstrated that magnesium reduced the receptor-mediated contraction of the rabbit corpus cavernosum and enhanced the relaxation of this tissue induced by sodium nitroprusside, bethanechol, and ATP.     

Effects of platelet-activating factor on nitrergic transmission in rabbit corpus cavernosum

AIM: The information currently available suggests that nonadrenergic noncholinergic (NANC) transmitters, particularly nitric oxide, are involved in the relaxation of penile erectile tissues. Platelet-activating factor (PAF) is a chemical mediator and is involved in many physiological and pathophysiological events. It is well known that several of the vascular actions of PAF are mediated by the generation of nitric oxide. We designed this study to test the hypothesis that PAF has an effect on NANC responses in rabbit corpus cavernosum strips. METHODS: Rabbit corpus cavernosum strips were precontracted with phenylephrine (10(-5) mol/L). Isometric tension changes produced by carbachol (10(-9)-10(-5) mol/L), sodium nitroprusside (10(-8)-10(-5) mol/L) and electrical field stimulation (for 10 s at sequential frequencies of 2, 4, 8, 16, and 32 Hz as square-wave pulses of 50 mV) were recorded with a pressure transducer. These relaxations were compared to those obtained in the presence of PAF. RESULTS: PAF had no effect on endothelium-dependent, endothelium-independent or electrical field stimulation-induced NANC relaxation responses in isolated rabbit corpus cavernosum strips. There was no statistically significant difference between the pD(2) and E(max) values for carbachol or sodium nitroprusside in the presence of PAF. CONCLUSIONS: Our results suggest that PAF does not modify the endothelium-dependent, endothelium-independent or electrical field stimulation-induced NANC relaxation responses in isolated rabbit corpus cavernosum strips.     

Comparative studies on intracellular calcium and nadh fluorescence of the rabbit corpus cavernosum

Erectile function (erection and detumescence) involves the complex interaction of direct neuronal stimulation of corporal smooth muscle, neurohumoral release of specific endothelial contractile and relaxant factors, and secondary modulation by a variety of putative neuropeptides and vasoactive modulators. Using surface spectrofluorometry, we have correlated spontaneous contractile activity and the contractile response to field and pharmacological agents with intracellular calcium and NADH metabolism. The results demonstrate that the corpus cavernosal tissue has very unusual properties. Spontaneous contractile activity is correlated with a phasic increase in intracellular calcium. However, spontaneous contractile activity is most often correlated with a bi-phasic effect on the ratio of NADH/NAD. At the start of the spontaneous contraction, there is a sharp phasic increase in NADH/NAD; peak contractile force occurs simultaneous with a phasic decrease in this ratio showing that at peak force generation, there is a decrease in the level of intracellular energy. Phenylephrine stimulation results in an increase in intracellular calcium in proportion to the increase in tension; however, phenylephrine stimulation at low concentrations results in a net increase in the NADH/NAD ratio whereas high concentrations of phenylephrine result in a net decrease in the NADH/NAD ratio. In general, field stimulation results in a decrease in tension at low frequencies, a biphasic response at midfrequencies, and a contraction at high frequencies. These contractile responses are directly related to alterations in the intracellular concentration of calcium. That is, a decrease in tension is preceded by a decrease in intracellular calcium while an increase in tension is preceded by an increase in intracellular free calcium. Field stimulation results in a rapid and phasic alteration in the NADH/NAD ratio; however, the NADH/NAD response can be either an increase, decrease, or biphasic response. There does not appear to be a consistent relationship between the contractile/relaxant response to field stimulation and altered NADH/NAD ratio. Finally, ATP, bethanechol, and nitroprusside induce a decrease in the basal tension of the corpus cavernosal strips which corresponds with a decrease in the NADH/NAD ratio. However, whereas nitroprusside relaxation is correlated with a decreased intracellular calcium level, both ATP and bethanechol stimulate an increase in intracellular free calcium. These studies indicate that the response of the corpus cavernosal tissue to both field stimulation and pharmacological agents is complex and may involve both direct and indirect actions of a variety of cellular mediators on the corporal smooth muscle. © 1994 Wiley-Liss, Inc.     

The participation of adenosine receptors in the adenosine 5''-triphosphate-induced relaxation in the isolated rabbit corpus cavernosum penis

AIM: To investigate the participation of adenosine receptors in the adenosine 5'-triphosphate (ATP)-induced relaxation in the corpus cavernosum penis (CCP) of rabbits. METHODS: The ATP-induced relaxation was assessed on the noradrenaline precontracted CCP of rabbits in the presence and absence of 8-(3-chlorostyryl)caffeine (CSC); an adenosine A(2A) receptor antagonist; alloxazine and MRS1754; adenosine A(2B) receptor antagonists; and ARL67156, an inhibitor of ecto-nucleoside triphosphate diphosphohydrolases. RESULTS: Adenosine and ATP relaxed the noradrenaline precontracted CCP of rabbits in a concentration-dependent manner. The adenosine- and ATP-induced relaxations were suppressed by alloxazine and MRS1754, but not by 8-(3-chlorostyryl)caffeine. ARL67156 potentiated the ATP-induced relaxation but not the adenosine-induced one. MRS1754 suppressed the ATP-induced relaxation potentiated by ARL67156. CONCLUSIONS: The above results suggest that, in the CCP of rabbits, the adenosine receptor mediating adenosine-induced relaxation is of the A(2B) receptor and the ATP directly causes relaxation through the A(2B) receptor on the CCP.