Temperature induced reactive oxygen species (ROS) in rat liver mitochondria

Abstract

Mitochondria (Mt) are highly dynamic organelles that exhibit morphological and biochemical changes during physiological cell metabolism and stress responses. Age-related diseases, including cancer, type 2 diabetes, Alzheimer, Parkinson diseases, show clear correlation with Mt dysfunction and reactive oxygen species (ROS). We have focused our study on response of Mt from normal tissues to hyperthermia that might affect healthy tissues when neighbouring tumours are treated by thermoablation or explosion to mild hyperthermia. We investigated the generation of ROS in isolated liver Mt derived from 1 to 7 months Wistar rats, both genders at 37–45 C temperature range. Internal ROS generation was determined fluorimetricaly with dihydrodichlorofluorescein diacetate (H2DCFDA) and external – with Amplex Red. The results showed that at 37 C much less ROS are generated by female rat Mt, as compared to male rat Mt. The difference for internal ROS generation was much larger (30% less in female than in male Mt) than that for external ROS production (about 10%), though statistically significant difference was found for 2 month old rats only. Rising temperature above normal, the amount of external ROS increased but the age and gender determined differences became smaller. Temperature induced external Mt ROS generation for young rats was less 8% and 12% for male and female at 40 C (compared to 37 C) and 14% and 18% at 45 C, respectively; than 6–7 month rats ROS generation at 40 C was higher 14 ir 17% for male and female and 26% and 34% at 45 C respectively. At 45 C the amount of internal ROS was 22% less in female Mt. The highest response to hyperthermic stress was found in 2 month female rat Mt at 45 C temperature – internal ROS content at 45 C was higher by 1.6 times comparing to that at 37 C.