Linoleic Acid Prevents Chloride Influx and Cellular Lysis in Rabbit Renal Proximal Tubules Exposed to Mitochondrial Toxicants

Abstract

Despite many studies elucidating the mechanisms of necrotic cell death, the role of fatty acids released during necrosis remains to be determined. The goals of this study were to determine whether linoleic acid could protect rabbit renal proximal tubules (RPT) from necrotic cell death associated with mitochondrial dysfunction and oxidative injury and to determine the mechanisms involved. Exposure to antimycin A (10 μM) for 1 h or hypoxia (perfusion with 95% N2/5% CO2) for 1 or 2 h induced approximately 70% cellular lysis, as measured by lactate dehyrogenase release, versus 10% in controls. Preincubation with linoleic acid (100 μM) fully protected RPT from cellular lysis. RPT were also protected from lysis if linoleic acid was added 15 min after the addition of antimycin A. Measurements of free intracellular Ca2+ concentrations showed that linoleic acid did not prevent the rise in intracellular Ca2+ associated with a 30-min exposure to antimycin A. However, the influx of extracellular 36Cl− following a 30-min exposure to antimycin A was ameliorated in the presence of linoleic acid. Linoleic acid did not prevent cellular lysis after exposure to hypoxia/reoxygenation (1 h/1 h) or t-butyl hydroperoxide (500 μM, 3 h). These data suggest that linoleic acid protects RPT during the late phase of cell death associated with inhibition of the electron transport chain but not oxidative injury. Several other fatty acids also protected RPT from lysis, and structure–activity relationship studies suggest that a free carboxyl terminus and at least one double bond are required for this action.