Yang, Huan

The antihypertensive influence of fish oil is controversial, and mechanisms remain unclear. We tested the hypothesis that fish oil reduces mean arterial pressure (MAP) via reductions in muscle sympathetic nerve activity (MSNA). Because the inverse relation between fish oil and hypertension appears to be dependent on the degree of hypertension, we also tested the hypothesis that fish oil would elicit more dramatic reductions in MAP and MSNA in prehypertensive (PHT) compared to normotensive (NT) subjects. Resting MAP, MSNA, and heart rate (HR) were examined before and after 8 wk of fish oil (9g/day) or placebo (olive oil; 9g/day) in 38 NT (19 fish oil; 19 placebo) and 29 PHT (15 fish oil; 14 placebo) volunteers. Fish oil did not alter resting MAP, MSNA, or HR in either NT (71±2 to 71±2 mmHg; 11±2 to 10±1 bursts/min; 80±1 to 80±1 beats/min) or PHT (88±2 to 87±1 mmHg; 11±2 to 10±2 bursts/min; 73±2 to 73±2 beats/min) subjects. However, when NT and PHT groups were consolidated, a significant correlation was observed between changes in MAP and changes in MSNA in the fish oil group (r=0.354, p=0.035). In conclusion, fish oil did not alter neural cardiovascular control in NT or PHT. However, interindividual MAP responses to fish oil appear to be moderately associated with changes in MSNA, suggesting that the sympathetic nervous system may contribute to the inconsistent antihypertensive response of fish oil. Supported by NIH (HL‐088689).