《膀胱beta受体》由会员分享，可在线阅读，更多相关《膀胱beta受体（5页珍藏版）》请在金锄头文库上搜索。
1、Br.J.Pharmacol.(1992),107,803-807Apossibleroleofdecreasedrelaxationmediatedby 3-adrenoceptorsinbladderoutletobstructionbybenign prostatichyperplasiaToshihikoTsujii,*HiroshiAzuma,*TomohiroYamaguchial-adrenoceptor;P-adrenoceptor;adenylatecyclaseIntroductionBenignprostatichyperplasia(BPH)occursinthemaj
2、orityof theagingmalepopulationandthebladderoutletobstruction causedbyBPHisoneofthemostcommonlyencountered disordersaturologyclinics.However,thespecificfeaturesof theprostaticadenomapredisposingtothedevelopmentof bladderoutletobstructionhavenotbeenwellexplored. Humanhyperplasticprostatictissueshavebe
3、enfoundto revealamarkedcontractileresponsetonoradrenaline(NA), whichisantagonizedbypretreatmentwithphentolamine,an a-adrenoceptorantagonist(Caineetal.,1975).Thesefindings haveledtoaproposalthatbladderoutletobstructionby BPHiscomposedofstaticanddynamiccomponents.The formercomponentisthephysicalobstru
4、ctionproducedby thepresenceofthehyperplastictissueitself,whereasthe latterfactoristhetoneoftheprostaticsmoothmuscle regulatedbytheautonomicnervoussystem(Caine,1986).A verydensenetworkofadrenergicnervefibreshasbeenfound histologicallydistributedwithinthesmoothmusclelayerof theprostaticglandularstroma
5、(VaalastiHedlundetal.,1985;Yokoyamaetal.,1985; Yamadaetal.,1987).Thesestudiesdemonstratedthat humanprostatictissuecontainedasubstantialnumberof highaffinityal-adrenoceptorsandthatcontractionofpros- taticsmoothmusclewasmediatedbyax-adrenoceptors. There havebeenveryfewstudies,however,ontheproper- ties
6、ofP-adrenoceptorsinhumanprostates.Inthepresent study,wehaveinvestigatedthebindingandfunctionalpro-Authorforcorrespondence.pertiesof13-aswellasa,-adrenoceptorsinhyperplasticand non-hyperplasticprostatictissueswithradioligandbinding studiesandinvitroisometrictensionexperimentsandthe resultsindicateapo
7、ssibleroleofthereducedrelaxationof prostaticsmoothmusclemediatedbyP-adrenoceptorscont- ributingtothebladderoutletobstructionbyBPH.MethodsProstatictissuesHumanprostatictissueswereobtainedatoperationfrom45 malesagedfrom42to82yearsofage(median70.0years); 32byopensubcapsularprostatectomyassurgicaltreatm
8、ent ofBPHand13byradicalcystoprostatectomyforbladder cancer.Thelatterpatientgroupincludedthosewhohad neithersymptomsofbladderoutletobstructionnoran enlargedprostatebyrectalexaminationandservedascont- rols.AllofthepatientswithBPHhadurinaryobstructive symptomssuchasurinaryretention,residualurinegreater
9、 than50ml,urinaryfrequenciesandlowurinaryflowrateby uroflowmetry.Eachsampleofprostatictissuewasdivided intotwoorthreeportionsofapproximatelyequalvolume andusedforradioligandbindingassayandinvitroisometric tensionexperiments.RadioligandreceptorbindingassayPreparationofcrudemembranefractionsImmediatel
10、yafter removal,aportionofthetissuewasimmersedin50mM ice-coldphosphatebuffer(pH7.5),mincedwithscissorsand twicehomogenizedwithaPolytronHomogenizeratmax- imumspeedfor30sin15volumesofice-coldphosphate.“MacmillanPressLtd,1992804T.TSUJIIetalbuffer(pH7.5).Thehomogenateswerethencentrifugedat 1,000gfor10min
11、at40C.Thesupernatantswererecent- rifugedat100,000gfor60minat4C.Thefinalpelletswere resuspendedinfreshphosphatebufferasacrudemembrane fractionandwerestoredat-800Cuntiluse. Proteinconcentrationofeachmembranefractionwas measuredwithbovineserumalbuminasastandardbythe methodofLowryetal.(1951).Then,eachfr
12、actionwas adjustedwithphosphatebuffer(pH7.5)tocontain100pg protein100p-forbindingassayof3H-dihydroalprenolol (3H-DHA)or250ptgprotein100fl-for3H-prazosinassay.SaturationanalysisRadiolabelledligandsusedforsaturation analyseswere3H-DHA(95.9CimmolP)forP-adrenoceptors and3H-prazosin(76.6CimmolP)foral-adr
13、enoceptors.The mediumfortheassaywasadjustedto250p1containing 100p1icrudemembranefractions,150glphosphatebuffer (pH7.5)andradiolabelledligandsatconcentrationsspecified inFigures2and5.Eachassaymediumwasshakenfor 30minat37CandfilteredthroughWhatmanGF/Bglass fibrefilters.Thefilterdiscswerethenrinsedthre
14、etimeswith 2mlofice-coldphosphatebufferandplacedin16mlof scintillationfluid(Econofluor;NewEnglandNuclear ResearchProducts).Radioactivitieswerecountedwitha Packard460-CDscintillationspectro-fluorometer.InvitroisometrictensionexperimentsImmediatelyafterremoval,anotherportionoftheprostatic tissuewaspla
15、cedinice-coldmodifiedKrebssolution (pH7.4)whichcontained(mM);NaCl115.0,KCl4.7,MgSO4 1.2,CaCl22.5,KH4PO41.2,NaHCO325.0andglucose10.0. Afterremovaloffatandconnectivetissue,tissuestrips (about5xlmm,0.2gwetweight)werepreparedand mountedverticallyinorganbathscontaining20mlof modifiedKrebssolutionwhichwas
16、continuouslybubbled with95%02and5%CO2at37C.Oneendofeachstripwas anchoredtoametalhookatthebottomoftheorganbath andtheotherendwasconnectedtoaforce-displacement transducer(TB611T,NihonKohdenKogyoCO.).Isometric changesintensionwererecordedonapen-writingoscillog- raph(R-64,RikaDenkiCo.).Thelengthofthestripswas adjustedseveraltimesuntiltherewasastablebasaltissue tensionof1.0g.Beforestartingtheexperiment,thestrips wereallowedtoequilibrateforatleast40minintheorgan bathsandthebathsolu
