A single high-fat Western meal modulates vascular responsiveness to sympathetic activation at rest and during exercise in humans: a randomized controlled trial

A single high-fat Western meal transiently reduces endothelium-dependent vasodilation at rest, but the interaction with sympathetic vasoconstrictor activity during exercise remains unknown. Herein, we tested the hypothesis that a single high-fat Western meal would impair the ability of contracting skeletal muscle to offset vascular responsiveness to sympathetic activation during exercise, termed functional sympatholysis. In 18 (10 females/8 males) healthy young adults, forearm blood flow (Doppler ultrasound) and beat-to-beat arterial pressure (photoplethysmography) were measured during lower-body negative pressure (LBNP; -20 mmHg) applied at rest and simultaneously during low (15% maximum contraction) and moderate (30% maximum contraction)-intensity rhythmic handgrip exercise. The magnitude of sympatholysis was calculated as the difference of LBNP-induced changes in forearm vascular conductance (FVC) between handgrip and rest. Experiments were performed preprandial and 1 h, 2 h, and 3 h after a high- or low-fat meal. In the preprandial state, LBNP decreased resting FVC (Delta-54 +/- 10%), and these responses were attenuated during low (Delta-17 +/- 7%)- and moderate (Delta-8 +/- 6%)-intensity handgrip exercise. Following a high-fat meal, LBNP induced attenuated decreases in resting FVC (3 h postprandial, Delta-47 +/- 10%, P = 0.002 vs. preprandial) and blunted attenuation of FVC during low (3 h postprandial, Delta-23 +/- 8%, P = 0.001 vs. preprandial)- and moderate (3 h postprandial, Delta-16 +/- 6%, P < 0.001 vs. preprandial)-intensity handgrip exercise. The high-fat meal attenuated the magnitude of sympatholysis during low (preprandial, 38 +/- 7 vs. 3 h postprandial, 23 +/- 8%, P < 0.001)- and moderate (preprandial, 46 +/- 11 vs. 3 h postprandial, 31 +/- 10%, P < 0.001)-intensity handgrip exercise. The low-fat meal had no impact on these responses. In conclusion, a single high-fat Western meal modulates sympathetic vasoconstriction at rest and during low- and moderate-intensity handgrip exercise in young healthy adults. NEW & NOTEWORTHY We observed that a single high-fat Western meal, but not an isocaloric low-fat meal, attenuated the sympathetic vasoconstriction at rest and the ability of the active skeletal muscle to counteract the vascular responsiveness to sympathetic activation (i.e., functional sympatholysis) during low- and moderate-intensity rhythmic handgrip exercise in healthy young adults. Our findings highlight the potential deleterious vascular effect associated with the consumption of a Western diet.