Aquaporin 8 is involved in H O -mediated differential regulation of metabolic signaling by α - and β-adrenoceptors in hepatocytes.

Reactive oxygen species participate in regulating intracellular signaling pathways. Herein, we investigated the reported opposite effects of hydrogen peroxide (H O ) on metabolic signaling mediated by activated α - and β-adrenoceptors (ARs) in hepatocytes. In isolated rat hepatocytes, stimulation of α -AR increases H O production via NADPH oxidase 2 (NOX2) activation.

β- Adrenoceptors activate hepatic glutathione efflux through an unreported pathway.

The physiological regulation of hepatic glutathione efflux by catecholamines is poorly understood. The purpose of this work was to review the role of adrenergic receptors (AR) on total glutathione (G) efflux in rat liver. Two models were used: isolated hepatocytes and perfused livers.

Newly synthesized cAMP is integrated at a membrane protein complex signalosome to ensure receptor response specificity.

Spatiotemporal regulation of cAMP within the cell is required to achieve receptor-specific responses. The mechanism through which the cell selects a specific response to newly synthesized cAMP is not fully understood. In hepatocyte plasma membranes, we identified two functional and independent cAMP-responsive signaling protein macrocomplexes that produce, use, degrade, and regulate their own nondiffusible (sequestered) cAMP pool to achieve their specific responses.

NOX2 activated by α1-adrenoceptors modulates hepatic metabolic routes stimulated by β-adrenoceptors.

The NADPH oxidase (NOX) family of enzymes oxidase catalyzes the transport of electrons from NADPH to molecular oxygen and generates O(2)(•-), which is rapidly converted into H(2)O(2). We aimed to identify in hepatocytes the protein NOX complex responsible for H(2)O(2) synthesis after α(1)-adrenoceptor (α(1)-AR) stimulation, its activation mechanism, and to explore H(2)O(2) as a potential modulator of hepatic metabolic routes, gluconeogenesis, and ureagenesis, stimulated by the ARs. The dormant NOX2 complex present in hepatocyte plasma membrane (HPM) contains gp91(phox), p22(phox), p40(phox), p47(phox), p67(phox) and Rac 1 proteins.

Evidence that endogenous inosine and adenosine-mediated hyperglycaemia during ischaemia-reperfusion through A3 adenosine receptors.

1 The molecular mechanism underlying stress-induced hyperglycemia has not been comprehensively clarified. Recently, we demonstrated in ischaemia-reperfusion (I-R) stress-subjected liver that inosine and adenosine are mainly responsible for the hyperglycemia observed. 2 We aimed to advance in the knowledge of the role of inosine plus adenosine as mediators of hepatic-induced hyperglycemia detected after I-R in lower limbs.