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1、利尿药（Diuretics）Thetwenty-firstchapterdiureticsanddehydratingdrugsThefirstsectionoffersadiureticDefinition:adrugthatactsonthekidneys,increaseselectrolytesandwaterexcretion,andincreasesurineoutput.First,physiologicalbasisofdiureticactionTheformationofurineincludesglomerularfiltration
2、,reabsorptionandsecretionofrenaltubulesandcollectingducts.(1)glomerularfiltration(two)reabsorptionofrenaltubulesandcollectingducts1.proximalconvolutedtubules:65–70%Na+reabsorption2.mtal:30-35%Na+wasabsorbed,andthenthelowerwaterabsorption,NaClresorptiondependentluminalmembraneK+-Na
3、+-2Cl-transportsystem.3.distalconvolutedtubulesandcollectingducts:5-10%Na+reabsorption.TheproximalconvolutedtubuleproximaltotheluminalmembraneK+-Na+2Cl-mediatesthereabsorptionof10%Na+intheurine.Therefore,thedrugsthatinhibittheabsorptionofNa+inthissegmentcanproducemoderatediuretice
4、ffect.Atthesametime,thereisNa+-Ca2+exchangeinthissection.Two.Classification,functionalsiteandmechanismofdiureticscommonlyused(1)highlyeffectivediuretics(loopdiuretics)Drug:furosemide,miconazoleacid(diureticacid),BroometaNiAmyfurosemide(Furosemide,furosemide)[pharmacologicaleffects
5、]1.diureticeffect:fast,strongandshort.Thesiteofaction:themedullaryloop,theascendingbranch,themedullaandthecortexThemechanismofaction:InhibitionofmedullaryloopoftheascendingbranchdiameterNa+-2Cl--K+cotransporter(togetherwiththeCl-competitioninthevectorofCl-bindingsite),Na+,Cl-absor
6、ptiondown,thusaffectingtherenalconcentrationanddilutionfunction.IncreasingK+excretion-Na+excretionincreasesandpromotesK+-Na+exchange.Atthesametime,diuresiscausesthedecreaseofbodyfluid,increasesofreninandaldosteronesecretion,andexcretionofK+.Easytocausehypokalemiaandlowsaltsyndrome
7、.2.dilatedvessels:(1)dilationofrenalvessels,reductionofrenalvascularresistance,andincreaseofrenalbloodflow.(2)dilatationofsmallveins,reductionofleftventricularfillingpressure,andreductionofpulmonaryedema.Themechanismofvasodilationmayberelatedtothepromotionofprostaglandinsynthesisa
8、ndinhibitionofitsdecomposition.[c
