Aim: In the present study, we demonstrated that total cardiac 201Tl
uptake changes associated with histological findings in DOX-induced
early myocardial injury.
Method: Early DOX cardiotoxicity was induced in normal rats by giving
15 mg/kg DOX intraperitoneally. Cardiac uptake studies and the blood
sampling for creatine kinase (CK) and lactate dehydrogenase (LDH)
assay has been performed on the 3rd (acute phase) and 16th days
(subacute phase) after the treatment, respectively. Rats were killed
by heart puncture and the hearts removed by dissection at 60 min
after the injection of 7.4 MBq 201Tl. The ratio of total cardiac uptake
to the injected dose (%ID/g x BW, where ID is injected dose and BW is
body weight) was calculated.
Result: DOX led to a significant decrease in myocardial uptake of 201Tl
in both treatment groups (p<0.05). There was no significant difference
in the %ID/g x BW between acute and subacute phases (p>0.05). DOX
induced a significant increase in the levels of CK and LDH in serum,
indicating its early cardiotoxicity (p=0.01). DOX treatment produced
disorganization of myocardial fibers, vacuolation of the cardiac
myocytes and myocardial necrosis (p=0.01). These cardiomyocyte
injuries were accompanied by increased numbers of mononuclear cells
(p<0.05). LDH, CK, cardiyomyopathy and mononuclear cell infiltration
scores were not found significantly different between acute and
subacute phases (p>0.05).
Conclusion: The DOX-induced cardiac injury at early stage can be
evaluated by 201Tl and the findings may be associated with the
myocardial inflammation. Due to the complicated mechanism of DOX
injury, we believe that the development process of cardiac injury
and the pathological findings should be taken into consideration in
interpreting the radiopharmasotic studies to be conducted for the
evaluation of the early and late stage cardiac injuries.