ObjectivesTostudytheeffectsofbradykinin(BK)B2receptorblockadeoninfarctsizeandhemodynamicsaftermyocardialinfarction(MI)inratswithangiotensin-convertingenzyme(ACE)inhibitiontherapy.MethodsMIwasproducedbyligatingtheleftcoronaryartery.Theeffectsofenalapril(500μg/kg·day),enalapril(500μg/kg·day)withBKB2receptorantagonistHoe-140(500μg/kg·day),angiotensinII(AngII)type1(AT1)receptorantagonistlosartan(3mg/kg·day)oninfarctsize,leftventricularsystolicpressure(LVSP),cardiacoutputindex(CI)andstrokevolumeindex(SVI)wereobservedinratsafterMI.Treatmentswerestartedonthe2nddayafterMIandcontinuedforanother6weeks.ResultsEnalaprilreducedinfarctsizeandimprovedCIandSVIcomparedwiththeuntreatedMIgroup(P<0.05),andtheseeffectsofenalaprilweresignificantlybluntedbyconcomitanttreatmentwithHoe-140(P<0.05).Losartanwaslesseffectivethanenalapril.LVSPwereunchangedinthethreetreatmentgroups.ConclusionsBKcanreduceinfractsizeandimprovehemodynamicsinratsfollowingMI.ThecardioprotectiveeffectsofACEIpartlyresultfromtheactionofBKexertedthroughtheB2receptor.
