Cortical Na⁺,K⁺-ATPase Activity, Abundance and Distribution after in vivo Renal Ischemia without Reperfusion in Rats

Abstract

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.

Sex differences in the alterations of Na+,K+‐ATPase following ischaemia–reperfusion injury in the rat kidney

“…(1995), Kwon et al . (2000) and Coux et al . (2001); however, all of these observations were made on male rats.…”

“…The pathogenesis of ARF is clearly multifactorial; however, altered function of NKA is considered to be a central factor of impaired cellular sodium and water homeostasis. Ischaemia was reported to induce a marked decrease in NKA activity by Van Why et al (1994), Kim et al (1995), Kwon et al (2000) and Coux et al (2001); however, all of these observations were made on male rats.…”

Time dependent effects of gentamicin on the enzymes of carbohydrate metabolism, brush border membrane and oxidative stress in rat kidney tissues

“…The reabsorption of Na + ions by proximal tubular BBM is considered to be the major function of the kidney because the transport of other ions and various solutes depends directly or indirectly on Na + reabsorption (Coux et al, 2001). Since these transports depends on structural integrity of BBM and available energy as ATP which is supplied by various metabolic pathways, it is imperative that any alterations to these pathways caused by toxic insult would determine the rate of renal transport functions (Khundmiri et al, 2004(Khundmiri et al, , 2005Fatima et al, 2005).…”

Pharmacological activators of AMP‐activated protein kinase have different effects on Na+ transport processes across human lung epithelial cells

“…Thus, a reduction in ATP could lead to a decrease in Na + K + ATPase function. Certainly, a diminution of ATP in renal cortical tubular cells ( Coux et al ., 2001 ) and reduced ATP levels in rat cerebellar granule cells ( Petrushanko et al ., 2006 ) were associated with a reduction of Na + K + ATPase function. Moreover, Compound C has been shown to inhibit AICAR uptake into cells and subsequent accumulation of ZMP.…”