Gender-dependence of hyperthermia-induced changes in respiration of rat liver mitochondria

Abstract

The effect of hyperthermia on the respiration of liver mitochondria derived from animals of different genders was estimated. We compared the effect of heating in the febrile (40 °C) and supraphysiological (41–46 °C) temperature range on the respiration rate in metabolic state 2 (V2) and state 3 (V3) of isolated mitochondria derived from male and female rat liver. Our results indicate that an increase of temperature in the fever range activates female but inhibits male liver mitochondrial respiration in state 3. Female mitochondria are less sensitive to supraphysiological temperature hyperthermia (41–43 °C). However, a severe hyperthermia (44–46 °C) strongly inhibits and uncouples oxidative phosphorylation in mitochondria, but the temperature-induced increase in inner membrane permeability is stronger in female mitochondria. At 46 °C, independently of gender, mitochondria are completely uncoupled (V2 = V3) and are unable to phosphorylate ADP. The increased respiration rate in the uncoupled state proves that febrile temperature (40 °C) activates oxidation processes in liver mitochondria isolated from female rats. For this reason, at 40 °C the respiratory control index (RCI) decreases to a much lower extent in mitochondria derived from female liver. Keywords: liver mitochondria, hyperthermia, gender (sexual) dimorphism