Abstract

Lipolytic glycerol, released from adipocytes, flows through bloodstream to liver where it is transported into hepatocytes to supply gluconeogenesis. AQP9, an aquaporin membrane channel, has been often linked to the uptake of glycerol in hepatocytes; however, no direct experimental evidence has been provided, yet. Here, we address the question by employing a stopped flow light scattering approach using vesicles of hepatocyte basolateral plasma membrane (BLPM) prepared from mouse livers in various metabolic states.The movement of glycerol across the hepatocyte BLPM vesicles occurred by facilitated diffusion as indicated by the low Arrhenius activation energy (3.5 kcal/mol) characterizing the transport and the strong (>60%) inhibition seen after incubation with phloretin or HgCl2, two known AQP9 blockers. Fasting markedly increased both AQP9 expression and glycerol membrane permeability (Pgly) of BLPM in a time-dependent manner. In line with these results, the plasma glycerol levels of the examined animals changed accordingly to the extents of Pgly and AQP9 expression values. This was also in line with additional experiments where the Pgly of the liver vesicles of AQP9 knockout mice resulted markedly lower than the Pgly of wild type mice counterpart (5.43±0.2 vs. 10.03±0.6 x 10­3 mm/s, respectively; P<0.01). Overall, these results prove major functional relevance for AQP9 in hepatocyte glycerol uptake indicating AQP9 as a new player in metabolic and energy homeostasis.

Autore Pugliese

• Calamita Giuseppe , Portincasa Piero

Tutti gli autori

• CALAMITA G.;SVELTO M.;PORTINCASA P.

Titolo volume/Rivista

Non Disponibile

Anno di pubblicazione

2011

ISSN

1748-1708

ISBN

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Numero di citazioni Wos

Nessuna citazione

Ultimo Aggiornamento Citazioni

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Numero di citazioni Scopus

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Ultimo Aggiornamento Citazioni

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Settori ERC

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Codici ASJC

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