RESUMO
Infarct-avid radiopharmaceuticals are necessary for rapid and timely diagnosis of acute myocardial infarction. The animal model used to produce infarction implies artery ligation but chemical induction can be easily obtained with isoproterenol. A new infarct-avid radiopharmaceutical based on glucaric acid was prepared in the hospital radiopharmacy of the INCMNSZ. 99mTc-glucarate was easy to prepare, stable for 96 h and was used to study its biodistribution in rats with isoproterenol-induced acute myocardial infarction. Histological studies demonstrated that the rats developed an infarct 18 h after isoproterenol administration. The rat biodistribution studies showed a rapid blood clearance via the kidneys. Thirty minutes after 99mTc-glucarate administration the standardised heart uptake value S(h)UV was 4.7 in infarcted rat heart which is six times more than in normal rats. ROIs drawn over the gamma camera images showed a ratio of 4.4. The high image quality suggests that high contrast images can be obtained in humans and the 96 h stability makes it an ideal agent to detect, in patients, early cardiac infarction.
Assuntos
Ácido Glucárico/análogos & derivados , Isoproterenol/efeitos adversos , Infarto do Miocárdio/induzido quimicamente , Infarto do Miocárdio/diagnóstico por imagem , Compostos de Organotecnécio , Compostos Radiofarmacêuticos , Animais , Cardiotônicos/efeitos adversos , Ácido Glucárico/síntese química , Ácido Glucárico/farmacocinética , Masculino , Compostos de Organotecnécio/farmacocinética , Cintilografia , Compostos Radiofarmacêuticos/síntese química , Compostos Radiofarmacêuticos/farmacocinética , Ratos , Ratos WistarRESUMO
Radiolabelled somatostatin analogues have been used in diagnostic and therapeutic nuclear medicine to treat cancerous tumours. Lanreotide, a cyclic octapeptide, beta-naphthyl-peptide, with antiproliferative action on human small cell lung carcinoma was (188)Re labelled and characterised, and its biodistribution was studied in mice. Molecular modelling indicates that the lipophilic radiopharmaceutical might be an oxo-rhenium (V) penta-coordinated complex. The implanted human cervical tumour of epidermoid origin was positive for cytokeratins and Vimentin. Uptake of (188)Re-labelled peptide in the implanted tumour in athymic mice was 6.2+/-2.9% and was rapidly cleared via the hepatobiliary system. (188)Re-beta-naphthyl-peptide might be a potential therapeutic agent.