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High fructose diet effects cardiovascular function one day after a single wood smoke exposure in adult Wistar-Kyoto rats
Citation:
Little, G., M. Harmon, B. Martin, Y. Kim, C. King, Ian Gilmour, A. Farraj, AND M. Hazari. High fructose diet effects cardiovascular function one day after a single wood smoke exposure in adult Wistar-Kyoto rats. Society of Toxicology (SOT) - Virtual, NA, Virtual, March 14 - 18, 2021.
Impact/Purpose:
The purpose of this study was to determine the impact of a high-fructose diet on cardiovascular and metabolic responses in rats and the role it plays in modifying the effects of wildfire smoke.
Description:
Wildfires are extreme events that have significant potential to harm both healthy individuals and those with underlying conditions like cardiovascular disease. We previously demonstrated that exposure to a single episode of wildfire or wood smoke can alter homeostatic function and worsen cardiovascular responses in healthy animals. However, it is not well established how diet affects the cardiovascular response to wildfire smoke. High- fructose (HF) intake has been associated with the development of obesity, inflammation, increased oxidative stress, and autonomic imbalance. This study examines the effects of a HF (30% fructose, 0% sucrose) diet on cardiovascular responses to wood smoke (WS) in Wistar-Kyoto rats. We hypothesized that a HF diet would alter basic metabolism, body composition and hemodynamic function of the heart, and worsen the subsequent response to WS. Eight-week old Wistar Kyoto rats were placed on either a 30% HF or normal diet (ND) for seven weeks. Body composition was measured every three weeks for fat, lean, and fluid compartment percentages, and animal resting energy metabolism was analyzed using an indirect calorimeter. Following the respective 7-week diet, each group was exposed to 5 mg/m3 of flaming WS or filtered air (FA) for one hour. Twenty-four hours after the exposure, rats were anesthetized, and cardiac function was determined with echocardiography. There were no significant changes in body composition in HF rats compared to the control. Respiratory exchange ratio significantly decreased in the HF diet compared to the control in both the light and dark cycle. HF rats exposed to WS had a significantly longer isovolumic relaxation time when compared to ND exposed to WS. Additionally, HF exposed to WS had a higher left ventricular myocardial performance (MPI) than ND exposed to WS. Exposure to WS caused standard deviation between NN intervals (SDNN) to increase and root mean square of the successive differences (RMSSD) to decrease in ND rats, on the other hand, HF rats exposed to WS only had an increase in the latter and showed a trend towards increased SDNN. There were no significant differences in frequency domain parameters. These results indicate that a HF diet alters baseline cardiovascular function even in the absence of body composition changes in Wistar Kyoto rats and suggests that diet can predispose the cardiovascular system to adverse effects during and after a single one-hour smoke exposure. (This work does not reflect USEPA policy)