Omega-3 fatty acid supplementation augments sympathetic nerve activity responses to physiological stressors in humans. Journal   Hypertension. Citation   Hypertension. 44(5):732-8 Publication date   2004 Nov Authors   Monahan KD Wilson TE Ray CA Investigators   Kevin D Monahan Chester A. Ray Grant agencies   National Center for Research Resources National Cancer Institute National Institute on Deafness and other Communication Disorders National Heart, Lung, and Blood Institute Grants   NCRR C06 RR016499 NCI CA00207 NIDCD DC006459 NHLBI HL58503 NHLBI HL67624 NCRR M01 RR10732 Abstract   An inverse relation exists between omega-3 fatty acid intake and risk of cardiovascular disease development/mortality and sudden cardiac death in humans. Mechanisms underlying this cardioprotective effect are unknown, but could involve the autonomic nervous system. We tested the hypothesis that omega-3 fatty acid supplementation ("fish oil") would reduce muscle sympathetic nerve activity (MSNA) at rest and attenuate increases during physiological stressors. MSNA (peroneal microneurography) was measured during rest, ischemic handgrip to fatigue (IHG), and a cold pressor test (CPT). Measurements were obtained before (PRE) and after (POST) 1 month of daily ingestion of either fish oil (experimental group, n=9) or olive oil capsules (control group, n=9). MSNA at rest was comparable PRE and POST in control (3+/-1 versus 3+/-1 bursts/30 seconds) and experimental (4+/-1 versus 5+/-1 bursts/30 seconds) subjects. IHG and CPT increased MSNA in both groups PRE and POST. MSNA, arterial blood pressure, and heart rate responses to the stressors were similar PRE and POST in the control group. In contrast, MSNA responses to IHG (Delta4+/-2 and Delta9+/-2 bursts/30 seconds; P<0.05 for PRE and POST, respectively) and CPT (Delta4+/-1 versus Delta10+/-2 bursts/30 seconds; P<0.05) were augmented after omega-3 fatty acid supplementation whereas arterial blood pressure and heart rate responses were unchanged. These data indicate that 1 month of omega-3 fatty acid supplementation does not change MSNA at rest but augments sympathetic outflow to physiological stressors. The mechanism underlying augmented MSNA responses to physiological stressors after omega-3 fatty acid supplementation is unknown, but may involve impaired peripheral vasoconstriction.