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 (10F/8M) 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-intensity (30% maximum contraction) rhythmic handgrip. 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 1h, 2h, and 3h after a high- or low-fat meal. In the preprandial state, LBNP decreased resting FVC (∆-54±10%), and these responses were attenuated during low- (∆-17±7%) and moderate-intensity handgrip (∆-8±6%). Following a high-fat meal, LBNP induced attenuated decreases in resting FVC (3h postprandial: ∆-47±10%, P=0.002 vs. preprandial), and blunted attenuation of FVC during low- (3h postprandial: ∆-23±8%, P=0.001 vs. preprandial) and moderate-intensity handgrip (3h postprandial: ∆-16±6%, P<0.001 vs. preprandial). The high-fat meal attenuated the magnitude of sympatholysis during low- (preprandial: 38±7% vs. 3h postprandial: 23±8%, P<0.001) and moderate-intensity handgrip (preprandial: 46±11% vs. 3h postprandial: 31±10%, P<0.001). 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.