二氨基乙氧基双苯萘酯对豚鼠膀胱不同区域逼尿肌兴奋性的影响

目的初步探讨二氨基乙氧基双苯萘酯（2-aminoethoxydiphenyl borate,2-APB）对豚鼠膀胱不同区域逼尿肌兴奋性的影响。方法将豚鼠膀胱按解剖标志划分并切取不同部位组织块,制成逼尿肌肌条,置Kreb液孵育,通过离体逼尿肌肌条实验观察2-APB对豚鼠逼尿肌收缩活动频率、幅度变化的影响。结果应用2-APB后膀胱不同区域逼尿肌收缩频率和收缩幅度抑制程度不同,顶部抑制程度最高,体部次之,颈部最弱。结论膀胱逼尿肌不同区域兴奋性不同,可能与不同区域ICCs样细胞的分布差异有关。     

NANC神经递质对膀胱下尿路梗阻逼尿肌稳定性的影响

目的　观察非肾上腺素能非胆碱能 (NANC)神经递质对下尿路梗阻逼尿肌肌条自发性收缩频率及收缩幅度的作用。　方法　建立Wistar大鼠膀胱下尿路梗阻动物模型 ,6周后以充盈性膀胱测压的变化检测逼尿肌不稳定的发生率。制备离体逼尿肌肌条 ,观察NANC神经递质血管活性肠肽 (VIP)、三磷酸腺苷 (ATP)对肌条自发性收缩频率及收缩幅度的影响。　结果　大鼠膀胱下尿路梗阻 6周后逼尿肌不稳定发生率为 6 2 % ;VIP、ATP能明显抑制逼尿肌的自发性收缩 ,降低逼尿肌肌条自发性收缩频率及收缩幅度 (P <0 .0 5 ) ;梗阻后逼尿肌不稳定组、逼尿肌稳定组及对照组之间差别无显著性意义 (P >0 .0 5 )。　结论　VIP、ATP能显著抑制正常和梗阻后逼尿肌自发性收缩的频率及收缩幅度     

三磷酸肌醇对大鼠离体逼尿肌肌条自发收缩作用的影响

目的:观察三磷酸肌醇(IP3)对大鼠逼尿肌肌条自发收缩频率及收缩幅度的作用。方法:建立逼尿肌不稳定(DI)大鼠模型,制作大鼠离体逼尿肌肌条,比较同等张力下DI及逼尿肌稳定(detrusorstability,DS)组逼尿肌肌条自发收缩频率和收缩幅度的变化,观察不同浓度IP3及其抑制剂肝素对二组肌条自发收缩频率和收缩幅度的影响。结果:大鼠膀胱下尿路梗阻6周后DI发生率为57.4%。同等张力下,DI组肌条自发收缩频率显著高于DS组(P<0.01),收缩幅度显著低于DS组(P<0.01)。IP3能显著增加DI、DS大鼠逼尿肌肌条自发收缩频率及收缩幅度(P<0.01),肝素能显著抑制DI鼠逼尿肌肌条的自发收缩频率(P<0.05),但对其收缩幅度没有显著影响(P<0.05)。结论:IP3能显著提高大鼠逼尿肌肌条自发收缩频率和收缩幅度,DI逼尿肌自发兴奋性升高可能与IP/Ca2 信号通路的改变有密切联系。     

非胰岛素依赖型糖尿病大鼠膀胱兴奋性自律性以及舒缩功能的改变

目的研究非胰岛素依赖型糖尿病(NIDDM)大鼠的逼尿肌功能变化情况，为进一步阐明糖尿病膀胱病变的发病机理提供实验依据。方法制造NIDDM大鼠模型，以正常大鼠为对照，分别进行残余尿测定，在体膀胱灌注测压观察膀胱最大容量、膀胱顺应性改变和最大逼尿肌收缩强度(即瓦特因子)以及采用离体逼尿肌条研究膀胱兴奋性、自律性及收缩力变化。结果糖尿病组大鼠膀胱逼尿肌兴奋性明显低于对照组，自律性呈现先高后低趋势，最大收缩力和平均收缩力较对照组降低；膀胱顺应性升高，残余尿增多、膀胱容量增大以及膀胱湿重增加。结论膀胱逼尿肌兴奋性降低是NVUDD的改变最早且最明显的指标。在糖尿病早期就存在逼尿肌自主节律性的变化。最初频率增加的原因可能是于逼尿肌兴奋性降低的代偿所致，其后表现为频率降低则是失代偿的结果。糖尿病对于膀胱收缩、舒张功能均有损害作用，从而导致膀胱顺应性改变。     

膀胱出口梗阻对逼尿肌兴奋性、收缩性及顺应性影响的实验研究

目的 探讨膀胱出口梗阻（ＢＯＯ）对逼尿肌兴奋性、收缩性、顺应性的影响及逼尿肌不稳定（ＤＩ）的发病机理。方法 建立Ｗｉｓｔａｒ大鼠ＢＯＯ动物模型,６周后行充盈性膀胱测压及离体逼尿肌条机械牵拉、电及胆碱类药物刺激试验。结果 ＢＯＯ后ＤＩ的发生率为６９％,逼尿肌顺应性升高;ＤＩ组与梗阻后稳定组及正常对照组相比,牵引逼尿肌致其出现心地的张力明显了低,电刺激产生的收缩力明显减弱;ＤＩ组逼尿肌胆碱类药物刺激产     

电压依赖性钾通道和逼尿肌不稳定关系的实验研究

目的观察电压依赖性钾（Kv）通道在逼尿肌不稳定（DI）中的表达变化及作用，探讨DI的发生机理及Kv通道作为治疗靶点的可行性。方法25只雌性Wistar大鼠建立膀胱出口部分梗阻模型，6周后行膀胱测压获得DI模型。制备逼尿肌肌条，离体收缩实验观察Kv通道阻断剂对逼尿肌肌条自发性收缩功能的影响；RT-PCR技术检测逼尿肌中Kv通道mRNA的表达。10只正常大鼠为对照组。结果Kv通道阻断剂4-氨基吡啶干预后，对照组逼尿肌肌条的收缩频率、幅度变化率分别为（84．3±23．8）％、（45．9±16．1）％，DI组分别为（34．2±11．4）％、（14．2±5．1）％，DI组均低于对照组（P〈0．05）。对照组逼尿肌中Kv通道亚型Kv2．1、Kv1．5的相对含量分别为0．75±0．11、0．61±0．09，DI组分别为0．65±0．09、0．39±O．07，DI组Kv通道含量减少，其中Kv1．5减少更明显（P〈0．01）。结论Kv通道反馈调节逼尿肌收缩，此机制在DI组明显减弱，可能导致逼尿肌收缩过度活跃。DI组Kv通道作用下调可能与逼尿肌中Kv通道亚型特别是Kv1．5的mRNA表达减少有关。Kv1．5也许可以作为治疗DI的较好靶点。     

糖尿病大鼠膀胱重构中M3受体改变的实验研究

目的:研究病程24周的2型糖尿病大鼠膀胱重构时,逼尿肌收缩功能的改变和M3受体含量及其基因转录水平的改变情况,并探讨二者之间的相关性。方法:2d龄雌性Wistar大鼠随机分成实验组和正常对照组,应用链脲佐菌素腹腔注射并结合高糖高脂饮食进行2型糖尿病大鼠动物模型制备。于糖尿病病程24周时进行下列实验:应用离体膀胱灌注方法观察逼尿肌收缩功能的变化;应用RT-PCR和Western blotting方法观察逼尿肌M3受体mRNA和蛋白表达的变化。结果:2型糖尿病组大鼠逼尿肌收缩功能低于正常对照组,为(16.52±2.97)cmH2O/100mgVS(25.66±3.56)cmH2O/100mg;2型糖尿病组大鼠逼尿肌M3受体mRNA和蛋白的表达均高于正常对照组,分别为(65.27±4.61)%VS(37.53±4.02)%和(45.19±2.37)%VS(23.67±2.85)%。结论:本研究证实了2型糖尿病大鼠在病程24周时膀胱逼尿肌的收缩力降低,但M3受体的生物合成却上调,这种不平行现象可能是病变进展的表现,为深入研究糖尿病膀胱病的发病机制提供了有价值     

糖尿病对膀胱逼尿肌兴奋性、收缩性及顺应性影响的实验研究

目的:探讨糖尿病(DM)对膀胱逼尿肌兴奋性、收缩性、顺应性的影响及糖尿病神经源性膀胱尿道功能障碍(NVUDD)的发病机制.方法:建立SD大鼠DM动物模型,于10周后行充盈性膀胱测压及离体逼尿肌条机械牵拉、电及胆碱类药物刺激试验.结果:DM动物模型10周后不稳定膀胱(DI)的发生率为64.7%,逼尿肌顺应性升高;DI组、DM后稳定组与正常对照组相比,牵拉逼尿肌致其出现收缩时的张力明显降低,电刺激产生的收缩力明显减弱;DI组逼尿肌胆碱类药物产生的收缩力明显减弱.结论:DM后NVUDD的发生率较高,其逼尿肌的收缩功能受损较重,DNBUD的发生与逼尿肌自身的神经源及肌源性改变密切相关.     

α1D与α1A受体亚型对大鼠不稳定逼尿肌收缩功能的影响

目的研究α1D及α1A受体亚型对大鼠膀胱出口梗阻（BOO）引起的不稳定逼尿肌（D1）收缩性、自律性的影响。方法建立Wistar大鼠BOO模型，充盈性膀胱测压确定D1模型，通过离体肌条牵拉实验，记录高选择性α1D及α1A受体亚型拮抗剂作用下，D1组和假手术对照组肌条自发性收缩频率及收缩力变化。结果35只BOO模型大鼠存活32只，D1发生率为71．9％。在一定张力前负荷下离体逼尿肌均产生自发性收缩，D1组肌条自发性收缩频率及收缩力均明显高于对照组；α1受体激动剂苯福林（PE）可使肌条自发性收缩频率及收缩力增加，选择性α1A受体拮抗剂5-MU能降低[（2．43±0．71）次／min，（0．14±0．03）g]对照组肌条的自发性收缩频率（2．64±0．72）次／min及收缩力（O．20±0．04）g，也能拮抗[（2．37±0．57）次／min，（0．19±0．02）g]PE所致的对照组肌条收缩频率（4．22±0．37）次／min和收缩力（0．31±0．03）g的增加（P〈O．01），而对D1逼尿肌作用不明显。选择性α1D受体拮抗剂BMY7378能降低[（2．32±0．56）次／min，（0．18±0．04）g]DI组肌条的自发性收缩频率（5．06±1．02）次／min及收缩力（0．42±0．08）g，并拮抗[（4．28±0．71）次／min，（0.48±0．04）g]PE所致的肌条收缩频率（6．73±0．61）次／min和收缩力（0.95±0．07）g的增加，但对正常逼尿肌作用不明显。结论 α1受体兴奋可使逼尿肌收缩频率及收缩力增加，正常逼尿肌中α1受体主要通过α1A亚型发挥作用，而梗阻性不稳定逼尿肌则主要通过α1D亚型发挥作用。     

糖尿病大鼠膀胱收缩功能改变与M3受体关系的实验研究

目的探讨糖尿病性膀胱发病机制中逼尿肌M3受体的改变情况。方法以链脲佐菌素诱导2型糖尿病大鼠成模。应用尿动力仪检测逼尿肌收缩功能；Westernblot、RT—PCR方法检测膀胱M3受体含量。结果病程2周时糖尿病组大鼠膀胱逼尿肌收缩力增加伴M3受体表达增强；病程4周时糖尿病组大鼠膀胱逼尿肌收缩力低于正常对照组，但尚无统计学意义；病程12周时糖尿病组大鼠膀胱逼尿肌收缩力降低伴M，受体表达减少。结论膀胱收缩功能和M3受体蛋白含量及M3受体mRNA的含量三者呈同向变化关系。在糖尿病大鼠发病早期三者均升高，但是随着病程进展却都降低了。这可能是早期糖尿病性膀胱病变的发病机制之一。     

Antimuscarinic drug inhibits detrusor overactivity induced by topical application of prostaglandin E2 to the urethra with a decrease in urethral pressure

PURPOSE: Antimuscarinic drugs increase bladder capacity without prominent side effects such as urinary retention even when administered to patients with mild to moderate bladder outlet obstruction. Some mechanisms might exist in the urethra to compensate for the emptying function of the detrusor after the administration of antimuscarinic drugs. We investigated the influence of the antimuscarinic drug propiverine (Taiho Pharmaceutical, Tokyo, Japan) on urethral function. MATERIALS AND METHODS: Urethral pressure and rhythmic bladder pressure were simultaneously monitored in urethane anesthetized female Sprague-Dawley rats. Prostaglandin E(2) was continuously administered intravesically or intraurethrally to induce detrusor overactivity. To eliminate the influence of bladder activity and monitor urethral baseline pressure isovolumetric pressure of the urethra was then recorded after cystectomy and ligation of the external urethral meatus. Furthermore, in vitro contractile responses of the urethral circular smooth muscle to field stimulation were examined in the presence of propiverine, tamsulosin (Taiho Pharmaceutical), verapamil, omega-conotoxin and atropine (Sigma). RESULTS: Intravesical or intraurethral administration of prostaglandin E(2) significantly decreased the bladder contraction interval by 10.7% and 36.0%, respectively. Intra-arterial administration of 2 x 10(2) nM/kg propiverine significantly increased the bladder contraction interval in rats receiving intraurethral prostaglandin E(2) by 81.8% but it had no marked effect on rats receiving intravesical prostaglandin E(2). Significant decreases in urethral baseline pressure were found after propiverine administration. Field stimulation induced contraction was inhibited by propiverine and verapamil but not by tamsulosin, omega-conotoxin or atropine. CONCLUSIONS: These results suggest that the inhibitory effects of propiverine are more prominent in rats with detrusor overactivity induced by intraurethral prostaglandin E(2) than by intravesical prostaglandin E(2). Propiverine may compensate for detrusor function by decreasing urethral resistance in the voiding phase.     

光感基因调控技术对大鼠骶上脊髓损伤后膀胱尿动力学和肌电图的影响

目的观察光感基因调控技术对大鼠骶上脊髓损伤所致神经源性膀胱功能的影响。方法 50只大鼠经尿流动力学检查无异常后进行随机分组,并采用T10脊髓完全横断建立脊髓损伤动物模型,分为假手术对照组、脊髓损伤无蓝光刺激组和脊髓损伤蓝光刺激组。2周后进行膀胱尿动力学、肌电图测定。结果脊髓损伤蓝光刺激组大鼠膀胱逼尿肌肌条舒缩曲线大部分可见规律性变化,波形均匀一致;同时膀胱最大容量增加,内压降低,顺应性升高;而脊髓损伤无蓝光刺激组无上述变化。结论光感基因可以调节骶上脊髓完全性损伤后膀胱逼尿肌的收缩功能,对神经源性膀胱功能恢复有重要意义。     

大鼠膀胱ICC样细胞与逼尿肌神经调控关系的形态学研究

目的 从形态学上探讨膀胱ICC样细胞在逼尿肌神经调控中的作用.方法 采用透射电镜观察大鼠膀胱内ICC样细胞、神经和逼尿肌细胞之间的超微结构关系.通过c-kit免疫荧光染色对大鼠膀胱ICC样细胞进行鉴定,并通过c-kit与PGP9.5免疫荧光双标观察ICC样细胞与神经的结构关系.结果 透射电镜显示,ICC样细胞与逼尿肌细胞紧密相邻处可见典型缝隙连接.在局部区域可见ICC样细胞的突起与神经末梢联系紧密.c-kit免疫荧光染色显示,大鼠膀胱内ICC样细胞主要位于黏膜下层、肌束边缘以及肌细胞间.c-kit与PGP9.5免疫荧光双标显示ICC样细胞与神经末梢在结构上关系紧密.结论 从形态学上看,膀胱内ICC样细胞具备参与逼尿肌神经调控的结构基础,进一步从功能学上予以证实将有助于全面阐明逼尿肌神经调控理论.     

Effects of Ethanol on Responses of Isolated Rabbit Urinary Bladder and Urethra

Background Acute ethanol ingestion increases the risk of urinary retention in patients with benign prostatic hyperplasia (BPH). To elucidate the mechanism of this effect, we investigated the in vitro effects of ethanol on lower urinary tract function in rabbits.
Methods The responses to various stimuli of muscle strips isolated from male rabbit bladder and urethra were determined in the presence of 0%, 0.5%, 1.0%, and 3.0% ethanol.
Results Basal tension of tissue strips taken from the bladder and the urethra was reduced by ethanol in a dose-dependent manner, as were bladder contractions induced by field stimulation, bethanechol, and ATP. Ethanol also reduced phenylephrine-induced contractions of the prostatic urethra. A high (3%) concentration of ethanol significantly reduced KCI-induced contraction of both the bladder and urethra, as well as urethral relaxation induced by field stimulation following contraction with 200μol/L phenylephrine.
Conclusion Responsiveness of the rabbit lower urinary tract was significantly reduced by exposure to ethanol. A similar decrease in tonus and contractility of the detrusor and inhibition of relaxation in the prostatic urethra may lead to urinary retention in men following acute ingestion of ethanol.     

The elusive electromyogram in the overactive bladder: a spark of understanding

It has been said that a technique capable of recording a urinary bladder electromyogram could be useful in the clinical evaluation of the detrusor neuropathies and myopathies implicated in the generation of lower urinary tract symptoms. However, in contrast to electromyography of skeletal and cardiac muscle, detrusor smooth muscle electromyography has remained in its infancy despite 50 years of scientific effort. The principal problems appear to be isolation of the real signal from artefacts, and the doubtful existence of electromyographic activity during cholinergic muscle contraction. The discovery of purinergic neuromuscular transmission in the overactive human bladder has renewed interest in detrusor electromyography as, in contrast to cholinergic mechanisms, purinergic mechanisms can generate extracellular electrical activity. In this paper, the development and validation of a novel technique for recording electrical activity from neurologically intact guinea-pig and human detrusor in vitro is described. A purinergic electromyographic signal is characterised and it is shown that detrusor taken from overactive human bladders has a greater propensity to generate electromyographic activity than normal by virtue of an aberrant purinergic mechanism.     

Aging effects on contractility of longitudinal and circular detrusor and trigone of rat bladder.

PURPOSE: Aging is associated with bladder dysfunction, including difficult voiding and urinary leakage. Voiding involves reduction in the bladder lumen in all dimensions brought about by contraction of the meshwork of longitudinal, circular and oblique layers of detrusor smooth muscles. Most in vitro physiological studies of the effects of aging on bladder function used the longitudinal detrusor. To understand the region specific effects of aging on bladder function the contractile responses of longitudinal and circular detrusor, and trigone segments of the bladder from young and old rats were monitored. MATERIALS AND METHODS: These studies were performed using male Fisher 344 rats 6 months (young) and 27 months (old) old obtained through the National Institute on Aging. Each rat was anesthetized and the bladder was isolated. From each bladder a strip of longitudinal detrusor, circular detrusor and trigone was isolated and mounted in an in vitro multi-muscle chamber containing normal physiological solution at 37C. Isometric contractions of the 3 bladder strips were monitored after electrical field stimulation, 120 mM. potassium and 1 to 1,000 microM. bethanechol using a digital oscilloscope. RESULTS: In longitudinal detrusor from old rats there was no significant difference in the contractions evoked by electrical stimulation or high potassium but there was a significant reduction in contractions evoked by bethanechol compared with the responses of longitudinal detrusor from young rats. In circular detrusor from old rats there was a significant increase in contractions evoked by electrical stimulation and a slight increase in contractions produced by high potassium but no significant change in contractions evoked by bethanechol compared with the responses of circular detrusor from young rats. In trigone from old rats there was a significant decrease in contractions evoked by electrical stimulation, high potassium and bethanechol compared with young trigone. CONCLUSIONS: The reduction in contractions evoked by bethanechol suggests an age related reduction in muscarinic receptors in the longitudinal detrusor of aged rats. An increase in contractions evoked by electrical stimulation without a change in contractions evoked by bethanechol suggests a decrease in compliance caused by an increase in collagen in the circular detrusor of aged rats. A general decline in all contractile responses, including those evoked by high potassium, suggests reduced membrane depolarization in the trigone of aged rats. The effect of aging is specific to different regions and functional components of the bladder, probably due to changes in muscarinic receptors, collagen and depolarization.     

Control of the unstable urinary bladder by graded thermoelectric cooling of the spinal cord

OBJECTIVE: To evaluate local lumbosacral spinal-cord cooling (a novel technique for neuromodulating urinary bladder reflexes) for its feasibility in possible clinical use, by determining the efficacy and the optimum temperature for suppressing reflex urinary incontinence in two rat models of neurogenic urinary bladder instability. MATERIALS AND METHODS: Overactivity of the detrusor muscle was induced by inflammation of the urinary bladder in a group of rats. A second group of rats was examined 6 weeks after complete midthoracic spinal cord transection, when all animals had developed neurogenic bladder hyper-reflexia. The intravesical pressure, urethral pressure and electromyographic (EMG) activity of the external urethral sphincter (EUS) were recorded simultaneously during repetitive local cooling and re-warming of the dorsal L6/S1 spinal cord segments, using a thermoelectric cooling device. RESULTS: Spinal cord cooling at L6/S1 had no influence on the recorded values at >26 degrees C, but markedly suppressed detrusor contraction frequency at 21- 25 degrees C. Cooling to <20 degrees C completely and reversibly eliminated inflammation-induced bladder contractions in rats with an intact neural axis and significantly reduced the contraction amplitudes (mean reduction 61%) and duration of contractions in spinally transected rats. Cooling simultaneously increased tonic EUS EMG activity and urethral perfusion pressure in both experimental groups, indicating closure of the urethral outlet. Cooling of adjacent spinal cord segments had no influence on bladder and urethral functions. CONCLUSION: Cooling the dorsal spinal cord at the origin of the parasympathetic innervation of the bladder can be used to reversibly suppress bladder instability with simultaneous closure of the urethral outlet. Therefore, local spinal cord cooling, e.g. as an implantable thermoelectric device, may offer a suitable method to treat detrusor overactivity and restore continence.     

The functional effects of a c-kit tyrosine inhibitor on guinea-pig and human detrusor

OBJECTIVE: To describe the effect of a specific c-kit receptor inhibitor (imatinib mesylate) on human detrusor strips in vitro and guinea-pig cystometry in vivo, and to show histological data suggesting differences in the distribution of interstitial cells of Cajal (ICC)-like cells in 'normal' and overactive human detrusor, as these cells have been identified as possible mediators of spontaneous activity and excitability in bladder smooth muscle. MATERIALS AND METHODS: Specimens of human detrusor were stained immunohistochemically with a c-kit antibody. Human detrusor strips were mounted in a superfused organ-bath apparatus, and smooth muscle contraction was evoked with carbachol and electrical field stimulation in the presence and absence of imatinib mesylate. Also, guinea-pig urodynamic studies were conducted before and after i.v. administration of imatinib mesylate, and changes in bladder variables and spontaneous activity were recorded. RESULTS: Imatinib mesylate (10(-6)M) inhibited evoked smooth muscle contraction and spontaneous activity in overactive human detrusor, with less effect on normal human tissue. Imatinib mesylate (10(-5)M) improved bladder capacity, compliance, voided volumes, urinary frequency, and reduced contraction thresholds and spontaneous activity during guinea-pig cystometry. c-kit labelling showed significantly more ICC-like cells in overactive human detrusor than in normal specimens. CONCLUSION: c-kit receptor blockers have inhibitory effects on guinea-pig and overactive human detrusor, possibly via c-kit receptors on bladder ICC-like cells. This and the possibility that there are more ICC-like cells in overactive bladder suggest that the c-kit receptor may provide a novel target for treating detrusor overactivity.     

Possible role of bioactive peptides in the regulation of human detrusor smooth muscle – functional effects in vitro and immunohistochemical presence

Results from basic research implicate a role for bioactive peptides in controlling the mammalian lower urinary tract. Although various peptides are assumed to be involved in the potentiaton or inhibition of cholinergic or purinergic activity in the urinary bladder, there is still much controversy regarding the mode of action and functional significance of such peptides in detrusor smooth muscle. Thus, we evaluated the functional effects of atrial natriuretic peptide (ANP), calcitonin gene related peptide (CGRP), endothelin 1 (ET-1), substance P (SP) and vasoactive intestinal polypeptide (VIP) on isolated strip preparations of human detrusor smooth muscle and determined the presence of those peptides in the human detrusor by means of immunohistochemistry. The effects of peptides on isometric tension of isolated detrusor strip preparations and on tissue levels of cyclic nucleotides cAMP and cGMP were compared to those of adenylyl cyclase activator forskolin (F), nitric oxide donor Na(+)-nitroprusside (SNP) and non-specific phosphodiesterase (PDE) inhibitor papaverine (P). The effects of the compounds on isometric tension of isolated human detrusor smooth muscle were examined using the organ bath technique. To determine time- and dose-dependent effects on cyclic nucleotide levels, bladder strips were exposed to increasing doses of F, SNP, P, ANP, CGRP and VIP, then rapidly frozen in liquid nitrogen and homogenised in the frozen state. cAMP and cGMP were extracted and assayed using specific radioimmunoassays. The presence of peptides was investigated by light microscopy using the Avidin-Biotin-Complex (ABC) method. F, P and VIP most effectively reversed the carbachol-induced tension of isolated human detrusor strips. Relaxing effects of ANP, CGRP and SNP were negligible. In contrast, ET-1 and SP elicited dose-dependent contractions of the tissue. The relaxing effects of F, P and VIP were accompanied by an increase in cAMP and cGMP levels, respectively. Light microscopy revealed positive immunostaining for CGRP, ET 1, VIP and SP in sections of the detrusor muscle coat. Our results suggest a possible importance of ET 1, SP and VIP in regulating detrusor smooth muscle contraction and relaxation. Even if a peptide is not synthesised, stored or released in a smooth muscle tissue and is, therefore, unable to reach its target cells under physiologic conditions, a functional effect on the tissue might be mediated by peptide-binding to specific cell surface receptors.     

Acute effects of serotonin on rat bladder contractility.

INTRODUCTION: The purpose of this study is to investigate in vitro the effects of serotonin on the rat detrusor. In particular, it examines which drugs inhibit the serotonin-induced detrusor contractions. MATERIALS AND METHODS: Isometric tension changes of isolated rat bladder muscle strips were recorded in an organ bath using a force transducer. Acute effects of serotonin (0.0001-0.01 mM) on resting tension were assessed. Electrical field stimulation (EFS); bethanechol (0.0001-0.01 mM); ATP (1-3 mM)- or KCl (63.5-254 mM)-induced contractions using an application in an organ bath were compared with serotonin-induced contractions. In order to examine the action mechanism of serotonin-induced stimulation, EFS-, bethanechol-, ATP- or KCl-induced contraction on serotonin treatment (0.001 mM) was assessed and serotonin (0.001-0.1 mM) was cumulatively added to the organ bath following preincubation with propranolol, ketanserin, tropisetron, propiverine, sodium nitroprusside or doxazosin. RESULTS: The serotonin-induced response has two phases: an initial transient contraction and a prolonged tonic phase. Serotonin produced a reversible and dose-dependent contraction of the detrusor strips. Responses to bethanechol significantly increased with a concentration of 0.001 mM serotonin (p < 0.05). There was no effect on the responses to ATP, KCl, or EFS on 0.001 mM serotonin. The 5-HT(2) receptor is mainly responsible for serotonin-induced contractions of the detrusor (p < 0.05), while the 5-HT(1) receptor is partially responsible. Doxazosin and propiverine each significantly suppressed the response to serotonin, while sodium nitroprusside and tropisetron each had no effect (p < 0.05). CONCLUSIONS: Because the 5-HT(2) antagonist blocked the effect of serotonin-induced bladder contractions and the stimulation of the adrenoreceptors, the 5-HT(2) antagonist seems to improve lower urinary tract symptoms.