Exercise training‐induced increase in coronary blood flow in Yucatan swine is blunted by hypercholesterolemia

We tested the hypothesis that aerobic exercise training would prevent a high‐fat/cholesterol diet‐induced attenuation of coronary blood flow (CBF) response to a dobutamine stress test in swine. Adult male Yucatan pigs were fed a low‐fat control diet (C) or a high‐fat/cholesterol diet (H; hypercholesterolemic; 46% kcal from fat, 2% cholesterol) for 20 wk. Pigs fed these diets were either exercise trained (X) or remained sedentary (SED); thus, we studied four groups: CSED, CX, HSED, HX. Exercise was treadmill running up to 75 min/day, 5 days/wk for 16 wk. Pigs were instrumented under anesthesia, and a coronary flow wire determined average peak velocity in response to intravenous dobutamine (5μg/kg/min for 5 min) followed by a 5‐min recovery period. Heart rate and blood pressure were continuously recorded. Intravascular ultrasound determined coronary cross sectional area for calculation of CBF (CBF = (1/2) APV*CSA). Rate pressure product (RPP) was used as an assessment of myocardial work, and CBF was standardized to myocardial work (CBF/work). Results: CBF/work ratio of CX was greater than all other groups (p<.05). CBF/work was also higher in the HX compared to CSED and HSED. Surprisingly, the CSED and HSED groups did not differ from each other. Conclusions: Exercise training increased the CBF/work ratio in control and H pigs, relative to sedentary; however, the high fat diet blunted the effects of exercise. Support: NIH HL52490, HL62552.