Cortical Na+,K+-ATPase activity, abundance and distribution after in vivo renal ischemia without reperfusion in rats

GABRIELA COUX; TRUMPER, L.; ELIAS, M. M.

Nephron

Karger

Año: 2001 vol. 89 p. 82 - 89

0028-2766

AbstractThe aim of our work was to study the changes in activity,abundance and distribution of sodium, potassium-adenosinetriphosphatase (Na+,K+-ATPase) in membranes ofcortical tubular cells in an in vivo model of ischemic injurywithout reperfusion. Na+,K+-ATPase, alkaline phosphatase(AP) activities and their distribution in membranesisolated from renal cortex using a Percoll gradientwere studied after different ischemic periods.Na+,K+-ATPase ·-subunit protein abundance was analysedby Western-blot. Plasma urea and cortical adenosine5’triphosphate (ATP) were also measured. In corticalhomogenates 5 min of ischemia promoted a diminutionin ATP content. Na+,K+-ATPase activity diminished after40 min and AP after 100 min of ischemia. Na+,K+-ATPaseactivity in the Percoll gradient fractions after 5 minpeaked at a higher density and was significantly decreasedafter 40 min. AP activity was decreased in typicallyenriched apical membranes after both times of ischemia.At each time studied Na+,K+-ATPase abundancewas increased in cortical homogenates and membranes.Our results showed opposite effects of ischemia onNa+,K+-ATPase activity and abundance. Increased levelsof Na+,K+-ATPase protein were observed. The enzymewould be rapidly delivered to membrane domains andbecome inactivated as ischemia persists