Low concentrations of
arachidonic acid monoepoxides protect against
ischemia/reperfusion injury. This study examined whether low concentrations of the
linoleic acid monoepoxide, cis-12,13-epoxy-9-octadecenoic
acid (12,13-EOA), protect renal cells against decreases in mitochondrial and transport functions induced by
hypoxia/reoxygenation. Primary cultures of rabbit renal proximal tubular cells (RPTC) were pretreated with diluent or 1, 5, or 10 microM
12,13-EOA for 1 h and exposed to 2 h
hypoxia/0.5 h reoxygenation in the absence of
12,13-EOA. Basal respiration,
oligomycin-sensitive oxygen consumption (QO2), and
ATP content decreased 31, 35 and 65%, respectively, following
hypoxia/reoxygenation.
Hypoxia/reoxygenation also increased mitochondrial membrane potential (DeltaPsi(m)). Pretreatment with
12,13-EOA prevented decreases in basal and
oligomycin-sensitive QO2s and increases in DeltaPsi(m). Despite the protection against decreases in mitochondrial function,
12,13-EOA pretreatment did not prevent the initial decrease in intracellular
ATP content following
hypoxia. However, pretreatment did accelerate the recovery of intracellular
ATP levels during reoxygenation. Pretreatment with
12,13-EOA also prevented
hypoxia-induced decreases in active Na+ transport.
Ouabain-sensitive QO2 (a marker of active Na+ transport) decreased 38% following
hypoxia/reoxygenation but was maintained in RPTC pretreated with 1, 5 or 10 microM
12,13-EOA prior to
hypoxia. Pretreatment of RPTC with the hydrolyzed product of
12,13-EOA,
12,13-dihydroxyoctadecenoic acid, did not have any protective effects against
mitochondrial dysfunction and decreases in active Na+ transport. Thus, this is the first report demonstrating that preconditioning of RPTC with low concentrations of
12,13-EOA, but not its hydrolyzed product, maintains mitochondrial respiration, accelerates restoration of
ATP levels, and prevents decreases in active Na+ transport following
hypoxia/reoxygenation.