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).

Omega‐3 fatty acids found in fish oil have been suggested to protect against cardiovascular disease, yet underlying mechanisms remain unclear. Given the well documented links between mental stress (MS) and cardiovascular risk, we hypothesized that fish oil would blunt blood pressure (BP), heart rate (HR), and muscle sympathetic nerve activity (MSNA) responsiveness to MS. Neural and cardiovascular responses to a 5 min mental arithmetic protocol were recorded in 67 non‐hypertensive subjects before and after 8 wks of fish oil (9g/day; n=33) or placebo (olive oil; 9g/day; n=34). Fish oil blunted HR reactivity to MS (group × condition × time interaction, P=0.012), but did not alter BP reactivity (interactions, P>;0.05). Fish oil blunted total MSNA reactivity to MS (interaction, P=0.039), but did not alter MSNA burst frequency and burst incidence reactivity (interactions, P>;0.05). Finally, fish oil significantly blunted calf vascular conductance (CVC) reactivity to MS (interaction, P=0.013), but did not alter forearm vascular conductance reactivity (interaction, P>;0.05). In conclusion, 8 wks of fish oil supplementation significantly attenuated HR and total MSNA reactivity to MS, and elicited a paradoxical blunting of CVC. These findings support and extend the growing evidence that fish oil may have positive health benefits regarding neural cardiovascular control in humans. Supported by NIH (HL‐088689).

Omega-3 fatty acids found in fish oil have been suggested to protect against cardiovascular disease, yet underlying mechanisms remain unclear. Despite the well-documented link between mental stress and cardiovascular risk, no study has examined neural cardiovascular reactivity to mental stress after fish oil supplementation. We hypothesized that fish oil would blunt the blood pressure, heart rate (HR), and muscle sympathetic nerve activity (MSNA) responsiveness to mental stress and/or augment limb vasodilation associated with mental stress. Blood pressure, HR, MSNA, forearm vascular conductance (FVC), and calf vascular conductance (CVC) responses were recorded during a 5-min mental stress protocol in 67 nonhypertensive subjects before and after 8 wk of fish oil ( n = 34) or placebo supplementation ( n = 33). Fish oil blunted HR reactivity to mental stress (group × condition × time interactions, P = 0.012) but did not alter blood pressure reactivity to mental stress (interactions, P > 0.05). Fish oil blunted total MSNA reactivity to mental stress (interaction, P = 0.039) but did not alter MSNA burst frequency and burst incidence reactivity (interactions, P > 0.05). Finally, fish oil significantly blunted CVC reactivity to mental stress (interaction, P = 0.013) but did not alter FVC reactivity (interaction, P > 0.05). In conclusion, 8 wk of fish oil supplementation significantly attenuated both HR and total MSNA reactivity to mental stress and elicited a paradoxical blunting of calf vascular conductance. These findings support and extend the growing evidence that fish oil may have positive health benefits regarding neural cardiovascular control in humans.