M. Mónica Elías

Rat kidney function related to tissue glutathione levels

Rat renal function was evaluated during acute depletion of glutathione (GSH) produced by different doses of diethyl-maleate (DEM). Significant alterations in renal function were observed when the GSH level diminished. The replenishment of GSH and the restoration of renal function were also investigated at various times after the injection. Similar time courses were observed of both the GSH level and renal functions, but the former was shortest. This suggests that the restoration to normal of GSH renal content was necessary in order to regain appropriate kidney function. Furthermore, the fact that impairment of sodium excretion occurred simultaneously with GSH depletion may be considered as evidence of the first event in GSH protective action. It may be hypothetized that the thick ascending limb is the principal renal target for this deficiency.

Renal function and cortical (Na(+)+K(+))-ATPase activity, abundance and distribution after ischaemia-reperfusion in rats.

The effects of ischaemic injury and reperfusion on renal function, cortical ATP content, alkaline phosphatase activity and (Na(+)+K(+))-ATPase activity and abundance in cortical homogenates and isolated basolateral and apical membranes were examined. Rats were submitted to 5 or 40 min of right renal artery occlusion and 60 min of reperfusion. Renal function of the ischaemic-reperfused kidney was studied by conventional clearance techniques. Our results show that 1 h of reperfusion after a short period of renal ischaemia (5 min) allows the complete restoration of the biochemical features of cortical cells and functional properties of the injured kidney. A longer period of ischaemia, such as 40 min, followed by 1 h of reperfusion showed functional and biochemical alterations. ATP recovered from 26% after 40 min of ischaemia to 50% of control values after 1 h reperfusion. However, renal function was strongly impaired. Brush border integrity was compromised, as suggested by AP excretion and actin appearance in urine. Although total cortical (Na(+)+K(+))-ATPase activity was not different from controls, its distribution in isolated apical and basolateral membranes was abnormal. Remarkably, we detected an increase in alpha-subunit protein abundance that may suggest that (Na(+)+K(+))-ATPase synthesis is promoted by ischaemia-reperfusion. This increase may play an important role in the pathophysiology of ischaemic acute renal failure.

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

The aim of our work was to study the changes in activity, abundance and distribution of sodium, potassium-adenosine triphosphatase (Na⁺,K⁺-ATPase) in membranes of cortical tubular cells in an in vivo model of ischemic injury without reperfusion. Na⁺,K⁺-ATPase, alkaline phosphatase (AP) activities and their distribution in membranes isolated from renal cortex using a Percoll gradient were studied after different ischemic periods. Na⁺,K⁺-ATPase α-subunit protein abundance was analysed by Western-blot. Plasma urea and cortical adenosine 5’triphosphate (ATP) were also measured. In cortical homogenates 5 min of ischemia promoted a diminution in ATP content. Na⁺,K⁺-ATPase activity diminished after 40 min and AP after 100 min of ischemia. Na⁺,K⁺-ATPase activity in the Percoll gradient fractions after 5 min peaked at a higher density and was significantly decreased after 40 min. AP activity was decreased in typically enriched apical membranes after both times of ischemia. At each time studied Na⁺,K⁺-ATPase abundance was increased in cortical homogenates and membranes. Our results showed opposite effects of ischemia on Na⁺,K⁺-ATPase activity and abundance. Increased levels of Na⁺,K⁺-ATPase protein were observed. The enzyme would be rapidly delivered to membrane domains and become inactivated as ischemia persists.

Tubular effects of acetaminophen in the isolated perfused rat kidney

AbstractThe effects of different acetaminophen (APAP) concentrations (1,5 or 10 mM) on renal function were investigated in the isolated perfused rat kidney (IPK). APAP was added to the perfusion media as a single dose after a equilibration time and control periods. Changes in fractional excretion of sodium (FENa), water

Role of lipid peroxidation on renal dysfunction associated with glutathione depletion. Effects of vitamin E

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Fibronectin expression in proximal tubules from ischemic rat kidneys without reperfusion

, glucose (FEglu) and in glomerular filtration rate (GFR) were measured. The lower concentration used only modified the

Evolution of renal function and Na + ,K + -ATPase expression during ischaemia-reperfusion injury in rat kidney

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