The Influence Of Endothelin On Prompt Change Of Cardiac Function At The Early Stage Following Severe Burn In Rats

The mechanism of myocardial damage and myocardial function decline at the early stage after severe burn is still unclear.To understand the relationship and mechanism between endothelin and myocardial function,this study observe the changes of myocardial function and myocardial blood perfusion at the early stage of postburn,especially within one hour ,as well as the changes of myocardial function and myocardial blood perfusion after blocking endothelin receptor.Methods1. Rats were inflicted with 30% TBSA of full-thickness burn,the changes of myocardial serum and tissue endothelin level,cardiac function and myocardial blood perfusion were observed 10minutes,30minutes,60minutes and 180minutes after burn .(Use ELISA to detect endothelin level, use left ventricle chatheterization to detect cardiac function, use fluorescence microsphere technique to detect myocardial blood perfusion)2. The changes of cardiac function and myocardial blood perfusion were observed after application of endothelin A receptor antagonist BQ-123 and endothelin A and B receptor antagonist PD142893 at the early stage of postburn.Results1. Cardiac function index (LVSP,±dp / dtmax) and myocardial blood perfusion decreased obviously ten minutes after severe burn, then began to increase until one hour, after that decreased once again until three hour ,while the heart rate showed a sustained decline. Endothelin concentration in myocardial increased obviously ten minutes after severe burn and remained at high level until three hour.However,endothelin concentration in serum has no change.2. Compared with burn group , BQ-123(30nmol/kg*min) group cardiac function ameliorated obviously ,but BQ-123(15nmol/kg*min) group cardiac function has no change.The myocardial blood perfusion of both group were not ameliorated obviously.Compared with BQ-123(15nmol/kg*min) group, BQ-123(30nmol/kg*min) group cardiac function index (LVSP,-dp/dtmax ) decline ameliorated obviously,whereas myocardial blood perfusion has no change.3. Compared with burn group ,PD142893(0.1mg/kg) group cardiac function and myocardial blood perfusion ameliorated obviously;Compared with BQ-123(30nmol/kg*min) group , PD142893(0.1mg/kg) group cardiac function index (LVSP) and myocardial blood perfusion decline ameliorated obviously .4. Compared with burn group , PD142893(0.4mg/kg) group cardiac function ameliorated obviously.Conclusions1. Cardiac dysfunction and myocardial damage occurred ten minutes following severe burn, which further proved the"shock heart"theory of ischemic/hypoxic injury.2. Local endothelin concentration in myocardium play an important role in the prompt reduction of cardiac function and myocardial blood perfusion .3. Endothelin,together with endothelin A receptor on myocardial cells cause the prompt reduction of cardiac function.4. ETA receptor and ETB receptor (primary ETB receptor) mediates the contraction of the cardiac blood vessels.5. Endothelin may act on the heart to produce negative chronotropic effect.