The aim of this study was to evaluate the cardiovascular autonomic control in trained youth male rats fed with high fructose diet. Weaned male Wistar rats (21 days) fed with fructose in drinking water (10%, 8wks) were randomized into sedentary (FS, n=5) and trained (FT, n=8), treadmill running,5 days/w, 60 min/d, during 8 wks) groups. Insulin resistance was evaluated by Glucose Tolerance Test. Arterial pressure signals were recorded using a data acquisition system (Windaq, 2KHz) in conscious and freely animals. Vagal and sympathetic tonus were measured by pharmacological blockade. The FT group had higher exercise capacity and lower insulin resistance compared to the FS group. Mean arterial pressure was similar between groups (FS: 124 ± 6 vs. FT: 125 ± 3 mmHg), however, the FT group presented resting bradycardia (339 ± 10 bpm) compared to the FS group (366 ± 13bpm). The sympathetic tone was lower in the FT group (41 ± 13bpm) compared to the FS (80 ± 6 bpm), however vagal tone was similar between groups. Thus, our results suggest that physical training during lifespan can be effective in attenuating the autonomic dysfunction resulting from high fructose consumption.
A western diet, high in fat and sugar, causes metabolic and cardiovascular dysfunction. The objective was to determine the effect of moderate swimming exercise (1 hr/d, 3 d/wk, n = 9–10/group) on the metabolic and cardiac responses to a high fat/sugar diet in mice. Groups are: Control (CON); Sedentary (SED, fat/fructose) and Exercise (EX, fat/fructose). Chow (60% fat) and fructose water (10%) were given ad libitum for 8 wk. Parameters measured were body fat, heart function (echocardiography, Echo), glucose, glucose tolerance (GTT) and liver glycogen. Mice gained body fat (up to 45%) on the fat/fructose diet with no difference between groups. Metabolic function was improved in the EX group as determined by glucose (SED>EX p <0.01) and GTT (SED>EX, p< 0.05). Insulin was lower in EX than SED, suggesting improvement in function. The diet increased liver glycogen, an effect which was improved in the EX group. Echo measurements showed impairment in cardiac function in the EX group. Relative wall thickness was higher in EX vs SED (0.35±0.01 vs 0.29 ±0.01, p<0.01). Fractional shortening was reduced in EX group (EX 0.31±0.01 vs SED 0.36±0.01, p < 0.01). This resulted in a reduced ejection fraction of ~37% vs 49% (EX vs SED). Data demonstrate that a moderate exercise paradigm combined with a high fat/sugar diet improves metabolic function but is detrimental to heart function in morbidly obese mice. Supported by NIH R01 HL093567
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