Protective Effect of Ligustrazine on Diaphragm Injury Induced by Doxoru bicin in Rats

Objective To explore the mechanism of doxorubi cin in impairing diaphragm and to investigate the prevention of doxorubicin -induced diaphragm i njury in rats.Methods Thirty SD rats were divided into norm al control group(n=10),model group(n=10)and ligustrazine group(n=10).Diaphragm strips was isolated to ob serve peak twitch ten-sion(Pt ),maximum titanic tension(Po),force -frequency curve,time to peak contraction(CT),half relaxation time (1/2RT),maximal rates of the rise of tension(+dT /dt max )and maximal rates of the decrease of t ension(-dT /dt max ).Meanwhile,the contents of superoxide dismutase(SOD)and malondialdehyde(MDA)in the diaphragm were also mea-sured.Results1)Pt,Po,+dT /dt max and -dT /dt max in the model group were lower than those in the control group(P0.01);the above four indexes in ligustrazine group did not differ from those in the normal control group and CT was pr o-longed as compared with that in the mo del group and in the normal control group(P0.01);stimulated by the frequen-cy of 10,20,40,60,100Hz ,diaphragm tension in the model group was obviously decreased as compared with that in the normal control group and ligustr azine group.2)SOD content was decreased and MDA increased in the control group as compared with the normal control gro up(P0.01);the differences of SOD and MDA were i nsignificant between control group and ligustrazine group.Conclusion Doxorubicin can depress the contraction of diaphragm and increase the pr oduc-tion of oxygen free radicals and redu ce their clearance;ligustrazine ca n protect diaphragm from damage by counteracting the above effects of doxorubicin.