Objective:ToinvestigatethedynamicsofplasmacAMP/Cgmpinpatientsduringcardiacsurgery,anditsrelationshiptotraumaticstress.Methods:Sixteenpatients,aged19.31years±10.4years,whounderwentanopenheartoperationwithcardiopulmonarybypass(CPB)andhypothermiawereservedassubjects.Thearterialplasmaconcentrationsofcyclicadenosinemonophosphate(Camp)andcyclicguanosinemonophosphate(Cgmp)weremeasuredbyradioimmunoassay2hoursbeforeoperation,afterheparinization,20minutesfollowingCPB,attheendoftheoperation,and24and72hourspostoperatively,respectively.Thepatients'preoperativebloodsampleswereheparinizedandthevenousbloodsamplesof30healthyblooddonorsweretakentomeasurethelevelsofCampandcGMPasheparinandnormalcontrolsseparately.Results:Therewerenostatisticaldifferenceamongtheheparincontrol,preoperativelevelandnormalcontrol.ThepeakvaluesofCampandCgmpoccurredduringCPBandplasmaCamplevelschangedsynchronouslywithintensitiesofoperativestimulustohumanbody.HowevercGMPlevelwasmainlyrelatedtotheoperativestimulustotheheartandCPB.TheCampvaluewaspositivelycorrelatedwiththeCgmpvalue(r=0.6313,P<0.001).Conclusions:Dynamicvariationofplasmacyclicribonucleotidecanbeconsideredasareferenceparameterforintensityoftraumaticstress.