| ObjectiveWe established stress cardiomyopathy rats model by dehydration and immobilization,and investigated whether dehydration could promote the development of stress cardiomyopathy.Methods55 male SD rats were randomly divided into 4 groups: normal group,dehydration group,braking group and dehydration combined braking group.Rats in the control group were given normal eating and drinking.Rats in the dehydration group were limited water intaking(50ml/day).Rats in the braking group were restricted activity6-8 hours per day,Rats in the dehydration combined braking group were restricted activity(6-8hours/day)and water intaking(50ml/day).We observed the ventricular wall motion per week by using 2D echocardiography.Left ventricular dysfunction accompanied by apical(typical)or non-apical(atypical)akinesis were defined as stress cardiomyopathy.Left ventricular end diastolic pressure(LVEDP),left ventricular systolic pressure(LVSP),maximum left ventricular pressure rise rate(+dp/dtmax)and maximum descent rate(-dp/dtmax)were measured weekly.The epinephrine and norepinephrine levels were tested by enzyme-linked immunosorbent assay.Left ventricular tissue was taken for HE staining.Results1.There were 33.3% rats showed globle left ventricular hypokinesis 26.7% rats showed left ventricular focal akinesis in dehydration group.There were 46.7% rats showed SIC changes(typically SIC changes accounted for 20%,atypical SIC changes accounted for 26.7%)in braking group.There were 53.3% rats showed SIC changes(typically SIC changes accounted for 20%,atypical SIC changes accounted for 33.3%)and 13.3% rats showed globle left ventricular hypokinesis in dehydration combined braking group.2.Compared with the control group,heart rates of rats in the dehydration group,the braking group and the dehydration combined braking group were significantly increased.(312.30±10.06 bpm,353.60±10.16 bpm,369.50±10.08 bpm,362.09±6.60 bpm respectively,P<0.05).3.Blood flow velocity of the left ventricular outflow tract(LVOT)in the dehydration group was increased in 1 week,and reached the peak level at the 3 week(the mean blood flow velocity of LVOT was 497.89±90.47mm/s,the peak velocity of LVOT was 497.89±90.47mm/s).Blood flow velocity of LVOT in the braking group reached the peak level at the 3 to 4 week(the mean blood flow velocity of LVOT was341.64±68.59mm/s,the peak velocity of LVOT was 587.46±78.82mm/s).The mean blood flow velocity of LVOT was 361.85±75.14mm/s,the peak velocity of LVOT was 569.11±68.94mm/s in dehydration combined braking group.4.Ventricular wall motion abnormalities appeared in the second week in the rats of dehydration group and dehydration combined braking group,they appeared at the third week in the braking group.5.In the dehydration group,20% rats showed ST segment depression and(or)low or inverted T wave.In the braking group,13.3% rats showed ST segment elevation,26.7% showed ST segment depression and(or)low or inverted T wave.In the dehydration combined braking group,20% rats showed ST segment elevation,26.7%showed ST segment depression and(or)low or inverted T wave.ECG of typical stress cardiomyopathy rats showed ST segment elevation,and ECG of atypical stress cardiomyopathy rats showed ST segment depression.6.Compared with the control group,the LVEDP of dehydration group?braking group and the dehydration combined braking group were significantly increased(96±6.09 mmHg,117.73±6.63 mmHg,131.92±8.02 mmHg,143.10±8.62 mmHg,respectively P<0.05).The level of LVSP were significantly increased(5.37±1.98 mmHg,9.42±2.89 mmHg,12.10±2.34 mmHg,11.05±2.53 mmHg,respectively P<0.05).The level of +dp/dtmax were significantly higher(3921.44±95.88mmHg/s,4311.72± 101.31 mm Hg/s,6354.43±151.50mmHg/s,5949.23±92.51mmHg/s,respectively P<0.05).The level of-dp/dtmax were significantly increased(3013.69±88.96 mmHg/s,3541.23±93.63mmHg/s,4060.42±124.62mmHg/s,3950.73±123.63mmHg/s,respectively P<0.05).7.Compared with the control group,the levels of NE were significantly higher in the dehydration group,the braking group and the dehydration combined brakinggroup(855.73±78.25ng/ml,1689.88±440.77ng/ml,1854.86±701.83ng/ml,1872.18±373.11ng/ml,respectively P<0.05).The level of EPI was also significantly increased(57.34±15.41ng/ml,135.94±65.31ng/ml,285.82±171.23ng/ml,264.26±112.10ng/ml,respectively P<0.05).8.Compared with the control group,the cardiomyocyte in dehydrated rats were smaller,the cytoplasm was stained deeply,the myocardial fibers were broken,and the inflammatory cells infiltrated.There was increased intercellular space,interstitial edema,myocardial fiber rupture,irregular arrangement of myocardial cells,partial myocardial necrosis and chronic inflammatory cell infiltration observed in the braking group.ConclusionIn the dehydration state,the flow velocity of the left ventricular outflow tract increased rapidly,and the left ventricular end diastolic pressure increased,which affected the wall motion and promoted the formation of stress cardiomyopathy. |
PDF Full Text Request