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