Insights into the mechanism of erythrocyte Na⁺/K⁺‐ATPase inhibition by nitric oxide and peroxynitrite anion

Abstract

Evidence shows that Na(+)/K(+)-ATPase from kidney, brain and liver is inhibited by nitric oxide (NO) and peroxynitrite anion (ONO(2) (-)), but the mechanism is unknown. The aim of the present work was to study the inhibitory effect of NO and ONO(2) (-) on erythrocyte Na(+)/K(+)-ATPase. Erythrocyte membranes were isolated from male Wistar rats by hypotonic washing. The membranes (free from haemoglobin) were incubated for Na(+)/K(+)-ATPase activity measurement at various concentrations of ATP in the presence or absence of 400 microM SNAP (an NO donor) or 100 microM SIN-1 (an ONO(2)(-) donor). At these concentrations, SNAP and SIN-1 released about the same amount (100 microM) of NO or ONO(2)(-), respectively, as monitored by measuring NO(2)(-) + NO(3)(-). Both SNAP and SIN-1 decreased V(max) by ca. 75% but they did not decrease the apparent affinity of the Na(+)/K(+)-ATPase for the substrate (a decrease of K(m) was even observed after SNAP treatment). The pattern of this inhibition is compatible either with oxidation of SH groups directly involved in ATP binding but in a way that is not surmountable by increasing the substrate concentration ("non-competitive") or with oxidation of SH groups located outside the active site of the enzyme but important for the activity of the enzyme.

The Neuroprotective Effect of Curcumin and Nigella sativa Oil Against Oxidative Stress in the Pilocarpine Model of Epilepsy: A Comparison with Valproate

“…, K ? -ATPase by oxidation of SH groups [86,87]. Curcumin treatment to pilocarpinized animals reversed the decrease in Na ?…”

N‐acetylcysteine attenuates the decline in muscle Na+,K+‐pump activity and delays fatigue during prolonged exercise in humans

“…Recently, William et al (2005) demonstrated that the nitric oxide (NO) donor sodium nitroprusside stimulated the Na + ,K + ‐pump in isolated myocardial cells. The effects of NO on Na + ,K + ‐pump activity appear to be tissue‐specific, as the NO donor S‐nitroso‐ N ‐acetylpenicillamine (SNAP) inhibited Na + ,K + ‐pump activity in rat kidney (Beltowski et al 2003), liver (Muriel & Sandoval, 2000) and erythrocytes (Muriel et al 2003). The peroxynitrite anion donor 3‐morpholinosydnonimine (SIN‐1) also inhibited Na + ,K + ‐pump activity in rat liver (Muriel & Sandoval, 2000).…”

Oxygen-induced Regulation of Na/K ATPase in Cerebellar Granule Cells

“…The other set of data on NO-induced inhibition of the Na/K ATPase is mostly obtained from cells or isolated protein treated with abnormally high levels of ONOO − or NO (micromolar concentrations of presynthesized ONOO − or excessive concentrations of NO donors: see e.g., Sato et al, 1997 ; Muriel and Sandoval, 2000 ; Muriel et al, 2003 ; Beltowski et al, 2004 ; Varela et al, 2004 ; Kocak-Toker et al, 2005 ). In all of these studies NO/ONOO − caused inhibition of Na/K ATPase resulting from the oxidation of the cysteine thiol residues of the catalytic α subunit or activation of the cGMP-PKG signaling cascade.…”