Exercise training improves insulin resistance and the functional vasodilatation in non‐exercising muscle in obese Zucker rats

Individuals with metabolic syndrome exhibit impaired functional vasodilation and exercise performance. We have demonstrated that insulin resistance impairs functional vasodilation via increased thromboxane receptor (TP)‐mediated vasoconstriction in the obese Zucker rats (OZ), a model of metabolic syndrome. We also showed that exercise training improves functional vasodilation in the spinotrapezius (exercising) muscle in OZ. In the current study, we examined the functional vasodilation in a nonCexercising muscle to determine whether there are global effects of exercise training to improve functional vasodilation. We hypothesized that exercise training would improve functional vasodilation in the cremaster muscle (non‐exercising) in OZ through a decreased TP‐mediated vasoconstriction. Six‐week old lean Zucker (LZ) and OZ were trained by treadmill (24 meters/min, 30minutes/day) for six weeks. Exercise workload, oral glucose tolerance test (OGTT), and the functional vasodilation in cremaster muscle were determined. OZ exhibited impairments in workload, OGTT, and functional vasodilation (41 ¡À 6%) as compared with LZ (80 ¡À 8%). SQ29548 improved the vasodilator responses in OZ (59 ¡À 7%) with no effect in LZ. The exercise workload doubled in trained LZ with a three‐fold increase in OZ, although the trained OZ was still less than the trained LZ. OGTT and functional vasodilation was improved in trained OZ (71 ¡À 6%) with no effect in trained LZ. SQ‐29548 had no effect on the vasodilator responses in the trained OZ. We conclude that exercise training improves functional vasodilation in the non‐exercised muscle via decreased TP‐mediated vasoconstriction. Based on our previous studies these results suggest that the improved insulin sensitivity is a global effect from exercise training to improve vascular responses.