The Experimental Research Of Sonodynamic Effect And Ventricular Function After Treatment On Rabbit Myocardium By Focused Ultrasound Wave Activating Hematoporphyrin

Objective: To observe the impact of sonodynamic effect and ventricular function after treatment on rabbit myocardium by focused ultrasound wave activating hematoporphyrin for experimental basis to treat arrhythmia and hypertrophic cardiomyopathy by sonodynamic therapy.Methods : All 24 Newland rabbits randomly divided into four groups: sham group (Sham,n=6),hematoporphyrin group (H,n=6),ultrasound group (U,n=6) and hematoporphyrin + ultrasound group (H+U,n=6).In H+U group, a dose of hematoporphyrin (2.5mg/kg) was injected by intravenous delivery. Two hours later, an ultrasound exposure on left ventricular myocardium was operated for 1 minute setting the acoustic power 2 w . In H group, the operation procedures were similar with the H+U group except for the ultrasound irradiation, The ultrasound exposure was performed in U group without administration of hematoporphyrin. However, all animals in Sham group didn,t givn hematoporphyrin and ultrasound treatment. After 4 d, the hemodynamics parameters were recorded by multichannel physiograph ,then all animals were sacrificed and hearts were harvestered. The necrotic area was calculated by 2,3,5-Triphenyltetrazolium chloride (TTC) staining and tissue structure was also observed by H&E.The immunohistochemical technique and TUNEL method were used to further study Bax,Bcl-2 expression and cell apoptosis .Results: 22 rabbits survived to 4 d . As for hemodynamics, there was no difference in all groups. The gross views: the abnormal myocardial tissue wan,t seen in H and Sham group ; there were clear white pot and red zone in the ultrasound exposure region in the U group ;in the H+U group ,the white zone wrapped by red zone was observed in ultrasound exposure region. The results of TTC staining :the myocardial tissue was stained red in the Sham and H groups ; there were black pots and white zone with length of (4.24±0.14)mm and depth of(1.25±0.32) mm in exposure to ultrasound in U and H+U groups , respectively. Histopathological analysis: the histological examination showed signs of myocardial cell injury in U group ,with cytoplasmic vacuoles of various sizes, leakage of erythrocytes and infiltration of inflammatory cells in ultrasound exposure zone. The exposed tissue resembled complete coagulated necrosis in H+U group, with disappearance of cell structure, leakage of a few erythrocytes and infiltration of inflammatory cells. TUNEL analysis: There were no apoptotic cells observed in H and Sham groups .The apoptotic cells(94.4±6.06)VS(167.8±8.49)in ultrasound-exposure groups was significant greater than that of Sham group in ultrasound exposure zone. Bax and Bcl-2 expression analysis: compared with H group, the average optical density value of Bax protein expression associated myocardial cells increased by 51.6%, 36.4% ,respectively in the ultrasound exposure area in H+U and U groups(P <0.01);the average optical density value of Bc1-2 positive expression in sham group increased significantly more than that of U and H+U groups (P<0.01);Compared with the Sham group, Bax,Bcl-2 expression were significantly statistical difference in U group(P <0.01).The optical density values of Bax,Bcl-2 were no significant statistic difference outside the region of ultrasound exposure in all groups.Conclusions: The significant sonodynamic effect caused necrosis and apoptosis of myocardiocytes exists in the process of treatment rabbit myocardium by focused ultrasound activating hematoporphyrin, and not affect ventricular function , that maybe a new choice for treatment of arrhythmia and hypertrophic cardiomyopathy.