Assuntos
Coração/diagnóstico por imagem , Miocárdio/metabolismo , Quinuclidinas/metabolismo , Quinuclidinil Benzilato/metabolismo , Receptores Colinérgicos/metabolismo , Receptores Muscarínicos/metabolismo , Tomografia Computadorizada de Emissão , Animais , Atropina/farmacologia , Radioisótopos de Carbono , Dexetimida/farmacologia , Relação Dose-Resposta a Droga , Frequência Cardíaca/efeitos dos fármacos , Fígado/metabolismo , Masculino , Papio , Quinuclidinil Benzilato/análogos & derivados , Receptores Muscarínicos/efeitos dos fármacosRESUMO
The distribution and kinetics of [11C]flunitrazepam in the brain were studied by positron emission tomography in the living baboon. Flunitrazepam was labelled on the methyl group with the 20 min positron emitter carbon 11. Fifteen to 25 mCi corresponding to 15-30 nmol were injected i.v. and sequential tomographic pictures of the brain were obtained. In some experiments, therapeutic doses of various benzodiazepines were injected i.v. subsequently in order to study the displacement of the radioactive ligand from brain structures. Lorazepam was shown to displace [11C]flunitrazepam from brain tissue, although other benzodiazepines (chlordiazepoxide, Ro 116896 and Ro 116893) led to a redistribution of the radioactive ligand in the body accompanied by an increase of brain radioactivity.
