Mitochondrial Respiration, Cardiac Function and Hemodynamics in Rats on High-Calorie Diets with Metabolic Syndrome and Diabetes

In a 24-week-long experiment, 31 rats were assigned to one of 3groups: a Control group receiving standard chow and water, a Fructose group receiving standard chow and a 20% fructose solution, or an STZ+lipids group that received a fat-enriched diet following a single 25 mg/kg streptozotocin injection at the onset of the diet. The STZ+lipids group exhibited hyperglycemia, hyperketonemia, and a decline in both heart rate and cardiac function. Conversely, there were no significant bio-chemical differences between the Fructose and Control groups. However, the Fructose group experienced a more pronounced decrease in heart function. Respirometric analyses unveiled a substantial increase in mitochondrial respiration across all adipose tissue types in both dietary intervention groups, with greater changes observed in the Fructose group. Correlation analyses demonstrated a positive association between respiratory indices and fat volume, heart function, and tissue blood flow in the Control group. In the STZ+lipids and Fructose groups, respiratory indices exhibited a positive correlation with heart rate and a negative correlation with dietary exposure characteristics. Overall, the markedly elevated mitochondrial respiration rate observed in rats subjected to hypercaloric diets was linked to characteristics indicative of dietary resilience, rather than measures of circulation.