RESUMO
PURPOSE: The aim of this study was to compare changes in respiratory dynamics starting immediately after administration of propofol alone or a combination of propofol and midazolam. MATERIALS AND METHODS: Twenty-seven healthy adult volunteers participated in a randomized crossover study of undergoing sedation with propofol alone (P group) or with a combination of propofol and midazolam (PM group). In the P group, continuous infusion of propofol through a target-controlled infusion (TCI) pump was started with the target effect site (ES) concentration set at 1.2 µg/mL. In the PM group, participants received a bolus administration of midazolam 0.02 mg/kg simultaneously with the start of continuous infusion of propofol through a TCI pump with the target ES concentration set at 0.8 µg/mL. The variables measured included the bispectral index (BIS) value, tidal volume (VT), percutaneous arterial oxygen saturation (SpO2), respiratory rate (RR), end-tidal carbon dioxide tension (ETCO2), estimated ES propofol concentration, and minute volume. RESULTS: BIS value, VT, SpO2, and ETCO2 decreased after sedative administration in the 2 groups. RR increased in the 2 groups. These changes occurred sooner in the PM group than in the P group. The ratio of change in VT to change in BIS value decreased in the 2 groups and was markedly smaller in the PM group than in the P group. Ratios of changes in SpO2, RR, and ETCO2 to change in BIS value increased in the 2 groups and were larger in the PM group than in the P group. CONCLUSION: Changes in respiratory dynamics occurred sooner in the PM group than in the P group. In the PM group, although VT began to decrease before the change in BIS value, the increase in RR caused the rate of decrease in SpO2 to be smaller than the rate of decrease in BIS value.
Assuntos
Hipnóticos e Sedativos/administração & dosagem , Midazolam/administração & dosagem , Propofol/administração & dosagem , Respiração/efeitos dos fármacos , Adulto , Estudos Cross-Over , Feminino , Voluntários Saudáveis , Humanos , MasculinoRESUMO
Hepatic gluconeogenesis is important for the maintenance of blood glucose homeostasis under fasting condition. Hepatocyte nuclear factor 4α (HNF4α) and FOXO1 transcription factors have implicated in this process through transcriptional regulation of glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK), which are rate-limiting enzymes in gluconeogenesis. In this study, we demonstrate that glycogen synthase kinase 3ß (GSK3ß) regulates the expression of gluconeogenic genes through HNF4α and FOXO1. Silencing of GSK3ß leads to reduction in the expression of gluconeogenic genes, including G6Pase, PEPCK, and peroxisome proliferator-activated receptor γ coactivator-1α. We show that GSK3ß directly binds to both HNF4α and FOXO1. Inhibition of GSK3 by SB-216763 abolishes HNF4α-mediated activation of G6Pase promoter. We also found that overexpression of GSK3ß potentiates G6Pase promoter activation by FOXO1 in a manner dependent on its kinase activity. Treatment of SB-216763 diminishes FOXO1-mediated activation of G6Pase promoter. Taken together, these results reveal a previously unrecognized mechanism for the regulation of gluconeogenic gene expression.
Assuntos
Fatores de Transcrição Forkhead/metabolismo , Regulação da Expressão Gênica , Glucose-6-Fosfatase/genética , Quinase 3 da Glicogênio Sintase/metabolismo , Proteínas de Choque Térmico/genética , Fator 4 Nuclear de Hepatócito/metabolismo , Proteínas Serina-Treonina Quinases/genética , Fatores de Transcrição/genética , Western Blotting , Células Cultivadas , Proteína Forkhead Box O1 , Fatores de Transcrição Forkhead/genética , Gluconeogênese , Glucose-6-Fosfatase/metabolismo , Quinase 3 da Glicogênio Sintase/genética , Glicogênio Sintase Quinase 3 beta , Proteínas de Choque Térmico/metabolismo , Fator 4 Nuclear de Hepatócito/genética , Humanos , Luciferases/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Fosfoenolpiruvato Carboxiquinase (ATP) , Fosforilação , Regiões Promotoras Genéticas/genética , Proteínas Serina-Treonina Quinases/metabolismo , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Fatores de Transcrição/metabolismoRESUMO
Protein arginine methylation is a common posttranslational modification catalyzed by a family of the protein arginine methyltransferases (PRMTs). We have previously reported that PRMT1 methylates Forkhead box O transcription factors at two arginine residues within an Akt consensus phosphorylation motif (RxRxxS/T), and that this methylation blocks Akt-mediated phosphorylation of the transcription factors. These findings led us to hypothesize that the functional crosstalk between arginine methylation and phosphorylation could be extended to other Akt target proteins as well as Forkhead box O proteins. Here we identify BCL-2 antagonist of cell death (BAD) as an additional substrate for PRMT1 among several Akt target proteins. We show that PRMT1 specifically binds and methylates BAD at Arg-94 and Arg-96, both of which comprise the Akt consensus phosphorylation motif. Consistent with the hypothesis, PRMT1-mediated methylation of these two arginine residues inhibits Akt-mediated phosphorylation of BAD at Ser-99 in vitro and in vivo. We also demonstrate that the complex formation of BAD with 14-3-3 proteins, which occurs subsequent to Akt-mediated phosphorylation, is negatively regulated by PRMT1. Furthermore, PRMT1 knockdown prevents mitochondrial localization of BAD and its binding to the antiapoptotic BCL-X(L) protein. BAD overexpression causes an increase in apoptosis with concomitant activation of caspase-3, whereas PRMT1 knockdown significantly suppresses these apoptotic processes. Taken together, our results add a new dimension to the complexity of posttranslational BAD regulation and provide evidence that arginine methylation within an Akt consensus phosphorylation motif functions as an inhibitory modification against Akt-dependent survival signaling.