Description | Isoprenaline(hydrochloride)isanon-selective beta-adrenergicreceptor agonist,usedforthetreatmentofbradycardiaandheartblock. |
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InVitro | Isoprenaline(300nM,3min)increasesparticulatecGMP-andcilostamide-inhibited,low-KmcAMPphosphodiesterase(cAMP-PDE)activitybyabout100%inintactratfatcells[1]. Isoprenalineinhibitsinsulin-stimulatedglucosetransportactivityinratadipocytes.Isoprenaline,intheabsenceofadenosine,promotesatime-dependent(t1/2approximately2min)decreaseintheaccessibilityofinsulin-stimulatedcellsurfaceGLUT4of>50%,whichdirectlycorrelatedwiththeobservedinhibitionoftransportactivity[2]. Isoprenaline(5nMand10mM)increasescyclicAMPlevelsandthiseffectispotentiatedbycilostamide(10mM),byrolipram,acyclicAMP-specificPDE(PDE4)inhibitor(10mM)andbycyclicGMP-elevatingagents(50nMANFor30nMSNPplus100nMDMPPO)[3]. IsoprenalineincreasesthetranscriptionalactivityofGialpha-2geneto140%ofthecontrolvalue,whereasgenespecifichybridizationforGsalpharemainsunchanged[4]. Isoprenaline(20nM)increasestheamplitudeoftotaliKandcausesanegativeshiftofapproximately10mVintheactivationcurveforiK,bothintheabsenceandinthepresenceof300nMnisoldipinetoblocktheL-typeCa2+current.Isoprenaline(20nM)increasesthespontaneouspacemakerrateofsino-atrialnodepacemakercellsby16%inrabbitisolatedpacemakercells[5]. |
ClinicalTrial | ViewMoreCollapse |
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CellAssay [3] | Cellsareseededin24-wellculturedishesatadensityof2to5×104cellsperwell.Experimentsareperformedafter3to5daysinculturewhencellshasreachedconfluence.Culturemediumisaspiratedandreplacedby0.5mLofPBScontainingthepharmacologicalagents.Treatmentsareperformedinquadruplicateat37°C.Thetype3,4and5PDEinhibitorscilostamide(10gM),rolipram(10pM)andDMPPO(10gM),respectively,areincubatedwithcellsfor30minbeforeadditionofadenylateorguanylatecyclaseactivators.CyclicGMPandcyclicAMParerespectivelyincreasedinRASMCbystimulationofparticulateguanylatecyclasewithANF(50nMfor10min)orfl-adrenoceptorswithisoprenaline(5nmfor5min).Attheendoftheincubationperiod,themediumisremovedandintracellularcyclicnucleotidesareextractedbytwoethanolic(65%)ishesat4°Cfor5min.Ethanolicextractsarepooled,evaporatedtodrynessbyaSpeed-Vacsystem.Thedriedextractisdissolvedinasuitableamountofassaybufferandcyclicnucleotidelevelsaremeasuredbyscintillationproximityassay.MCEhasnotindependentlyconfirmedtheaccuracyofthesemethods.Theyareforreferenceonly. References |
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