RESUMO
The concentration of thallium in body organs and brain regions was studied in rats as a function of the animals age from newborn to 20-days old. Thallium was analyzed at different times after a single sublethal i.p. injection of the metal (16 mg/kg). The results indicate that the brain is less permeable to thallium in the older animals, suggesting that reduced thallium transport into the brain is related to the establishment of the blood-brain barrier in the rats. Differences between weanling and newborn rats were also found in regard to regional distribution of thallium in the brain as the older animals showed a region-dependent distribution while newborn rats presented an homogeneous content of thallium among all regions.
Assuntos
Envelhecimento/metabolismo , Encéfalo/metabolismo , Tálio/farmacocinética , Animais , Animais Recém-Nascidos , Barreira Hematoencefálica/efeitos dos fármacos , Química Encefálica , Feminino , Injeções Intraperitoneais , Masculino , Ratos , Ratos Wistar , Tálio/administração & dosagem , Tálio/análise , Tálio/toxicidade , Distribuição TecidualRESUMO
Durante los últimos nueve años estudiamos cincuenta casos de intoxicación por talio. Veintiocho casos fueron mujeres y vientidos fueron hombres. Uno de los casos fue un recién nacido, cuya madre sufrió este tipo de intoxicación durante el tercer trimestre de su embarazo. Las edades variaron de un día hasta 84 años de edad y en todos los casos la fuente de talio fue una solución raticida administrada oralmente, excepto en el recién nacido en quien la vía de acceso fue a través de la placenta y en una paciente en que fue transdérmica. En veintitrés casos la intoxicación fue accidental, con fines suicidas en veintiuno y con fines homicidas en cinco. En un caso la fuente de intoxicación fue desconocida. En todos los casos los niveles de talio se midieron en la orina, en algunos en la sangre y en el líquido cefalorraquídeo. Las principales manifestaciones clínicas fueron las de una neuropatía periférica severa de tipo mixto, con dolor abdominal, náusea, vómito y alopecia y en algunos casos manifestaciones psiquíatricas. En varios casos se practicaron estudios electrofisológicos, biopsia de nervio con examen de microscopía electrónica en tres pacientes, resonancia nuclear magnética y tomografía axial computarizada de abdomen y de cráneo en dos pacientes. Sólo uno de los pacientes murió y el resto se recuperó prácticamente en forma completa. Se revisan la patofisiología y las bases farmacológicas del manejo de este tipo de neurointoxicación
Assuntos
Humanos , Recém-Nascido , Adolescente , Adulto , Pessoa de Meia-Idade , Masculino , Feminino , Penicilamina/administração & dosagem , Penicilamina/farmacocinética , Penicilamina/uso terapêutico , Intoxicação/diagnóstico , Intoxicação/fisiopatologia , Intoxicação/terapia , Reação do Azul da Prússia , Tálio/farmacocinética , Tálio/intoxicação , Tálio/toxicidadeRESUMO
New Zealand rabbits were used to determine the acute kinetics of the Tl+ ion (0 to 90 minutes) following intravenous administration of two doses of Tl+ (10 mg.kg-1 and 30 mg.kg-1). The rapid disappearance of Tl+ from the blood may be explained by means of an open parallel tricompartmental mamillary model. The most important pharmacokinetic parameters which changed with the dose were Vdl (0.61 +/- 0.08 1.kg-1 for the low dose and 0.59 +/- 0.10 1.kg-1 for the high dose); ABC0-90 (310 +/- 18 mg.ml-1 min-1 for the low dose and 942 +/- 107 Mg.ml-1 min for the high dose; Kd (0.026 +/- 0.005 min-1 for the low dose and 0.037 +/- 0.010 min-1 for the high dose). The importance of the values of the slopes alpha, rho & gamma found by residual methods are discussed and compared with the results reported by other authors working with other species and different times.
Assuntos
Tálio/farmacocinética , Animais , Compartimentos de Líquidos Corporais , Injeções Intravenosas , Masculino , Modelos Biológicos , Coelhos , Tálio/administração & dosagemRESUMO
This paper describes the acute effects produced by administering potassium (2.7 and 5.5 mg.per kg of weight) to rabbits intoxicated with 10 and 30 mg.kg-1 of thallium. Acute capture (90 minutes) of thallium by skeletal muscle, left ventricle, liver and renal medulla and cortex is studied. Different doses of thallium were found to modify the organic capture in the studied organs with quantitative differences. The administering of potassium also modified the magnitude of capture, in different magnitudes, in the various organs. The modification produced depends more upon the studied organ than on the dose of potassium given. The skeletal muscle seems to manage the thallium-potassium interaction depending on the activation of sodium-potassium ATPase. The liver does not seem to be directly affected by the thallium-potassium interaction. The left ventricle captures thallium very rapidly, and also seems to depend on the activation of sodium potassium ATPase, and potassium increases thallium capture. The renal medulla captures 4 to 5 times more thallium than its cortex and the high dose of thallium seems to saturate the medulla's capture. The renal cortex's capture was not renal elimination of thallium is activated by potassium. The renal cortex uptake was not modified by potassium but the renal thallium elimination seems to be activated by potassium. The uptake by the renal medulla is diminished by potassium, suggesting a thallium-potassium interaction similar to the competitive inhibition described by McCall et al. (1985).
Assuntos
Cloreto de Potássio/farmacologia , Tálio/farmacocinética , Animais , Transporte Biológico/efeitos dos fármacos , Interações Medicamentosas , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/metabolismo , Rim/efeitos dos fármacos , Rim/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Músculos/efeitos dos fármacos , Músculos/metabolismo , Especificidade de Órgãos , Coelhos , Tálio/intoxicação , Distribuição Tecidual/efeitos dos fármacosRESUMO
A biochemical study of experimental thallium intoxication in newborn rats and its morphological consequences upon the brain of developing animals was undertaken. The thallium content was analyzed in the following encephalic regions: hippocampus, hypothalamus, mesencephalon, cerebellum, and cortex. One day after application of the toxic substance, a homogeneous distribution of the metal in the brain was found. Thallium concentrations in the mentioned regions were twice as high as those found in an adult rat, at the same dosage, 20 newborn Wistar rats were used for the histopathological study. 5 remained as witnesses, the rest received a single injection of thallium of .07 ml. of a solution with a concentration of .32 mg/Kg. 3 rats were sacrificed at 24, 48 and 72 hours; 3 at 7 days and 3 at 51 days. The brain , sciatic and crural nerves were fixated in 10% formaldehyde for 15 days. Cuts in paraffin and frozen sections measuring between 5 and 7 microns were taken from the fragments of different areas. These were stained with aniline methods (Masson, Gallego and H-E) and silver-gold impregnation as modified by Río-Hortega.