Effect of acetaminophen on the membrane anchoring of Na+, K+ATPase of rat renal cortical cells

In previous works we reported that the administration of a toxic dose of acetaminophen (APAP) induces acute renal failure (ARF) and promotes changes on Na+, K+ATPase distribution in renal proximal plasma membranes. In the present work, we analyzed if APAP could promote the dissociation of Na+, K+ATPase from its membrane anchorage. The participation of calpain activation was also evaluated. We analyzed the Triton X-100 extractability of Na+, K+ATPase in freshly isolated cortical cell suspensions incubated with different APAP concentrations (0.1, 1, 10 and 100 mM). Both α1 and β1 subunits were studied by Western blot. APAP promoted the increment of both subunits abundance in the Triton-soluble fraction. Calpain activation was detected in the membrane fractions of cells incubated with APAP. Incubation with APAP 0.1, 1 and 10 mM did not promote an increment in LDH release compared with controls, while APAP 100 mM promoted an increased LDH release. Our results show that incubation of proximal cells with sublethal and lethal APAP concentrations promotes the detachment of Na+, K+ATPase from its membrane anchoring. Inhibition of calpain activation by SJA 7029 protected against APAP-induced membrane damage but not against APAP-induced increase of the Triton X-100 extractability of Na+, K+ATPase.