Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Medula Óssea/efeitos dos fármacos , Leucemia-Linfoma Linfoblástico de Células Precursoras/terapia , 8-Bromo Monofosfato de Adenosina Cíclica/administração & dosagem , Células da Medula Óssea , Criança , Etoposídeo/administração & dosagem , Humanos , Técnicas In Vitro , Metilprednisolona/administração & dosagemRESUMO
1. Alpha 2-Adrenoceptor antagonists [3H]yohimbine and [3H]RX 781094 and the partial alpha 2-agonist [3H]clonidine exhibited specific binding to plasma membrane fragments isolated from interscapular brown fat of 7-day-old rats. 2. Competition studies with epinephrine, yohimbine and practolol revealed that [3H]norepinephrine, the principal in vivo agonist acting upon brown adipocytes, can readily bind to alpha 2-adrenoceptors in brown fat of infant rats. 3. The presence of alpha 2-adrenoceptor subclass in brown fat of infant rats may play a role in the sympathetic regulation of this rapidly proliferating tissue.
Assuntos
Tecido Adiposo Marrom/metabolismo , Antagonistas Adrenérgicos alfa/metabolismo , Receptores Adrenérgicos alfa/metabolismo , Animais , Ligação Competitiva , Membrana Celular/metabolismo , Clonidina/metabolismo , Di-Hidroalprenolol/metabolismo , Dioxanos/metabolismo , Idazoxano , Cinética , Norepinefrina/metabolismo , Ratos , Ratos Endogâmicos , Ioimbina/metabolismoRESUMO
Mucosa isolated from the proximal third of the small intestine of infant rats had much lower cyclic nucleotide concentrations (expressed both per unit wet weight and per unit DNA content) than those determined in the intestinal wall. The steady-state concentrations of both cyclic AMP and cyclic GMP in jejunum showed dramatic increases during the first 5 d post partum. Another increase in cyclic nucleotide concentrations was observed in the isolated mucosa between d 15 and 21. Starvation for 24 h always resulted in lower intestinal cyclic nucleotide concentrations than those of the fed littermates. This effect was more pronounced in younger animals and more evident for cyclic AMP values. Three-week-old rats fed a high carbohydrate diet for 24-48 h exhibited more pronounced elevations in the concentrations of cyclic nucleotides from the jejunal mucosa than did rats fed a high fat diet.