RESUMO
Extracellular adenosine 5'-triphosphate (ATP) has significant effects on a variety of pathological conditions and it is the main physiological agonist of P2X7 purinergic receptor (P2X7R). It is known that ATP acting via purinergic receptors plays a relevant role on skin inflammation, and P2X7R is required to neutrophil recruitment in a mice model of irritant contact dermatitis (ICD).The present study investigated the effects of chemical irritant croton oil (CrO) upon ATP, ADP, and AMP hydrolysis in mice blood serum, and the potential involvement of P2X7R. The topical application CrO induced a decrease on soluble ATP/ADPase activities (~50 %), and the treatment with the selective P2X7R antagonist, A438079, reversed these effects to control level. Furthermore, we showed that CrO decreased cellular viability (52.6 % ± 3.9) in relation to the control and caused necrosis in keratinocytes (PI positive cells). The necrosis induced by CrO was prevented by the pre-treatment with the selective P2X7R antagonist A438079. The results presented herein suggest that CrO exerts an inhibitory effect on the activity of ATPDase in mouse serum, reinforcing the idea that ICD has a pathogenic mechanism dependent of CD39. Furthermore, it is tempting to suggest that P2X7R may act as a controller of the extracellular levels of ATP.
Assuntos
Nucleotídeos de Adenina/sangue , Dermatite de Contato/genética , Dermatite Irritante/genética , Receptores Purinérgicos P2X7/genética , Animais , Antígenos CD/sangue , Apirase/sangue , Óleo de Cróton/toxicidade , Dermatite de Contato/sangue , Dermatite de Contato/patologia , Dermatite Irritante/sangue , Dermatite Irritante/patologia , Modelos Animais de Doenças , Humanos , Hidrólise , Queratinócitos/efeitos dos fármacos , Queratinócitos/metabolismo , Camundongos , Nucleotídeo Desaminases/sangue , Antagonistas do Receptor Purinérgico P2X/administração & dosagem , Receptores Purinérgicos P2X7/sangueRESUMO
Forty-seven children (ASA I or II) were studied during nitrous oxide-oxygen, halothane anaesthesia. The dose-response curve for vecuronium was determined after the injection of a single bolus (40, 55 or 70 micrograms kg-1) to 33 patients. The ED50 and ED95 were 31 and 64 micrograms kg-1 respectively. Fourteen children received a larger dose (100 micrograms kg-1); good intubating conditions were obtained in all of these within 2 min. After a single bolus (100 micrograms kg-1) the duration of action was 36.5 min and the recovery index was 9.3 min. In patients who received small maintenance doses (25 micrograms kg-1) after a single bolus (100 micrograms kg-1) the recovery index after the last maintenance dose was not increased. There were no significant changes in heart rate or arterial pressure. In children, vecuronium has a short duration of action and lacks cumulative or cardiovascular side affects.