RESUMO
We investigated the effect of L-NAME, a nitric oxide (NO) inhibitor and sodium nitroprusside (SNP), an NO-donating agent, on pilocarpine-induced alterations in salivary flow, mean arterial blood pressure (MAP) and heart rate (HR) in rats. Male Holtzman rats (250-300 g) were implanted with a stainless steel cannula directly into the median preoptic nucleus (MnPO). Pilocarpine (10, 20, 40, 80, 160 æg) injected into the MnPO induced an increase in salivary secretion (P<0.01). Pilocarpine (1, 2, 4, 8, 16 mg/kg) ip also increased salivary secretion (P<0.01). Injection of L-NAME (40 æg) into the MnPO prior to pilocarpine (10, 20, 40, 80, 160 æg) injected into the MnPO or ip (1, 2, 4, 8, 16 mg/kg) increased salivary secretion (P<0.01). SNP (30 æg) injected into the MnPO or ip prior to pilocarpine attenuated salivary secretion (P<0.01). Pilocarpine (40 æg) injection into the MnPO increased MAP and decreased HR (P<0.01). Pilocarpine (4 mg/kg body weight) ip produced a decrease in MAP and an increase in HR (P<0.01). Injection of L-NAME (40 æg) into the MnPO prior to pilocarpine potentiated the increase in MAP and reduced HR (P<0.01). SNP (30 æg) injected into the MnPO prior to pilocarpine attenuated (100 percent) the effect of pilocarpine on MAP, with no effect on HR. Administration of L-NAME (40 æg) into the MnPO potentiated the effect of pilocarpine injected ip. SNP (30 æg) injected into the MnPO attenuated the effect of ip pilocarpine on MAP and HR. The present study suggests that in the rat MnPO 1) NO is important for the effects of pilocarpine on salivary flow, and 2) pilocarpine interferes with blood pressure and HR (side effects of pilocarpine), that is attenuated by NO
Assuntos
Animais , Masculino , Ratos , Pressão Sanguínea , Frequência Cardíaca , Agonistas Muscarínicos , Óxido Nítrico , Pilocarpina , Área Pré-Óptica , Salivação , Inibidores Enzimáticos , Infusões Parenterais , Agonistas Muscarínicos , NG-Nitroarginina Metil Éster , Nitroprussiato , Pilocarpina , Ratos Sprague-DawleyAssuntos
Ratos , Animais , Masculino , Angiotensina II/farmacologia , Ingestão de Líquidos/efeitos dos fármacos , Hemodinâmica/efeitos dos fármacos , Área Pré-Óptica/fisiologia , Soluções Hipertônicas/farmacologia , Órgão Subfornical/fisiologia , Angiotensina II/administração & dosagem , Pressão Sanguínea/efeitos dos fármacos , Encéfalo/patologia , Relação Dose-Resposta a Droga , Frequência Cardíaca/efeitos dos fármacos , Solução Salina Hipertônica/administração & dosagemRESUMO
Este artigo, de caráter introdutório, discute e revê algumas idéias a respeito do conceito de homeostase. Fatos e modelos temporais säo introduzidos para mostrar que existem mudanças de estado nos biossistemas que näo säo preditas pela homeostase. Conceitos de termodinâmica e de organizaçäo säo apresentados, fornecendo novas bases para se entender o estado de um biossistema