No abstract

Background: The biological effects of cigarette smoke are not fully known. To improve our understanding of the action of various chemical agents, we investigated the biodistribution of sodium pertechnetate (Na 99m TcO 4 ) in mice exposed to cigarette smoke.

The aim of the present study was to determine the effect of the oral ingestion of an extract of the herb Uncaria tomentosa (cat's claw) on the biodistribution of the radiobiocomplex sodium pertechnetate (Na 99m TcO 4 ) in rats. The animals (male Wistar rats, 2 months old, 180-220 g), were treated (1 mL) with an U. tomentosa extract (32 mg/mL, N = 5) or 0.9% NaCl solution (control, N = 5) for 7 days. After this period, Na 99m TcO 4 (3.7 MBq, 0.3 mL) was injected through the ocular plexus and after 10 min the rats were killed, the organs isolated and counted in a well-gamma counter. A significant (P < 0.05) alteration in Na 99m TcO 4 uptake i) from 0.57 ± 0.008 to 0.39 ± 0.06 %ATI/organ (P < 0.05) and from 0.57 ± 0.17 to 0.39 ± 0.14 %ATI/g (P < 0.05) was observed in the heart, ii) from 0.07 ± 0.02 to 0.19 ± 0.07 %ATI/g in the pancreas, and iii) from 0.07 ± 0.01 to 0.18 ± 0.07 %ATI/g (P < 0.05) in muscle after treatment with this extract. Although these results were obtained with animals, caution is advisable in the interpretation of the nuclear medicine examination when the patient is using this herb. This finding is probably an example of drug interaction with a radiopharmaceutical, a fact that could lead to misdiagnosis of the examination in clinical practice with unexpected consequences for the patient.

Many compounds affect the bioavailability of radiobiocomplexes as radiopharmaceuticals. Ginkgo Biloba extract (EGb) has several effects. The influence of an EGb on the bioavailability of the radiobiocomplex sodium pertechnetate (Na99mTcO4) and on the morphometry of the organs was evaluated. Rats were treated with EGb and Na99mTcO4 was injected. The animals were sacrificed; the radioactivity in the organs was counted. The results showed that EGb altered the Na99mTcO4 bioavailability in the kidneys, liver and duodenum. Morphometric analysis of the organs showed significant alterations (P<0.05), probably caused by metabolites generated by EGb and capable of altering the bioavailability of the Na99mTcO4.
Substâncias podem interferir na biodisponibilidade de radiobiocomplexos, como os radiofármacos. O extrato de Ginkgo Biloba (EGb) apresenta efeitos. Avaliou-se a influência de um EGb na biodisponibilidade do pertecnetato de sódio (99mTcO-4Na) e na morfometria de órgãos de ratos que foram tratados com EGb. 99mTcO-4Na foi injetado, os animais sacrificados e a radioatividade nos órgãos contada. Os resultados mostraram que o EGb alterou a biodisponibilidade do 99mTcO-4Na em rins, fígado e duodeno e alterações morfométricas significativas (p<0.05) foram encontradas. Sugere-se que o EGb poderia gerar metabólitos capazes de alterar morfometricamente os órgãos citados e alterar a biodisponibilidade do 99mTcO-4Na

28 de setembro, 87, Rio de Janeiro, RJ, Brasil, 2055 1-030. bemardo@uerj.br key words: Sechiunz edule, blood cells, technetium-99m, biodistribution, morphometry. summary.The evidence that drugs can affect radiolabeling or biodistribution of red cells in setting of nuclear medicine clinic has with to light only recently. A therapeutic drug can modify the nature/amount of technetium-99m ehTc) radiopharmaceutical bound to blood elements and this may result in a unexpected behavior of the radiopharmaceutical. Chayotte is used as food or as medication in popular medicine. We evaluated the influence of chayotte extract (macerated) on the biodistribution of sodium pertechnetate (gh"Tc04Na) in rats lVistar and on the morphometry of the red blood cells. The animals were treated during 60 days with chayotte extract. After that, Tc04Na was injected and the animals were sacrificed. The organs were isolated and counted in a well counter. The percentages of radioactivity (%AT0 in the organs were calculated. The analysis of the results have shown that there was a decrease of %AT1 in the lungs, stomach and thyroid. Histological preparations were carried out with the blood samples from the animals treated with chayotte during 15 days. Optical microscopy of red blood cells (RBC) showed important morphological alterations due to the treatment of the animals during 15 days with chayotte extract. The results could be justified by the metabolization of chayotte vegetable that could be capable to induce the generation of active metabolites with lesive properties in specific biological systems. The effects of the chayotte extract could also be due to a direct action of the compounds present in extract.