IQUIFIB   02644
INSTITUTO DE QUIMICA Y FISICOQUIMICA BIOLOGICAS "PROF. ALEJANDRO C. PALADINI"
Unidad Ejecutora - UE
artículos
Título:
Renal sodium-glucosse cotransporter activity and aquoporin-2 expression in rat kidney during chronic nitric oxide synthase inhibition
Autor/es:
MARÍA F ALBERTONI BORGHESE; MÓNICA P MAJOWICZ; MARÍA C ORTIZ; MARÍA F DELGADO; NORMA STERIN-SPEZIALE; NORBERTO A VIDAL
Revista:
Nephron Physiology
Editorial:
Karger
Referencias:
Año: 2007 vol. 107 p. 77 - 86
Resumen:
Abstract
Background/Aims: The renal sodium glucose cotransporter
(SGLT2) and the water channel aquaporin-2 (AQP2) play a
critical role in tubular sodium and water reabsorption and in
the regulation of extracellular fluid volume both in physiologic
and pathophysiologic conditions. However, there is little
information about SGLT2 and AQP2 expression and/or
activity in hypertension and there are no reports during
hypertension induced by chronic nitric oxide synthase (NOS)
inhibition. Methods: Hypertension was induced in rats by
oral administration of N G -nitro- L -arginine methyl ester ( L -
NAME) (20 mg/kg/24 h) for 6 (H6) or 12 (H12) weeks. SGLT2
activity was measured using _ - 14 C-methylglucose active uptake.
The expression level of transporters was assessed by
immunohistochemistry and/or immunoblotting. Results:
SGLT2 activity was reduced in both H6 and H12; this was due
neither to a decrease in SGLT2 expression nor to a change in
membrane phospholipid composition. In H6, AQP2 expression
diminished only in the inner medulla (IM), while in H12 it
diminished in both outer (OM) and IM. This reduced expression
of AQP2 may partially account for the increased urinary
volume and decreased urinary osmolality in H12, since
we obtained a strong correlation between AQP2 expression
and these urinary parameters in both OM and IM. Conclusion:
We propose that in rats in which hypertension is induced
by NOS inhibition, SGLT2 activity and AQP2 expression
are modified to compensate for the elevated arterial
pressure. However, we cannot discount the possibility that
the observed changes are due to the decrease in NO production
itself.