Lowering systolic blood pressure and increases in vasodilator levels in SHR with oral alpha-linolenic acid administration.

The present study attempted to clarify the antihypertensive effect and its mechanism when alpha-linolenic acid (ALA) is administered orally. For this purpose, 1 mL of flaxseed oil, which is rich in ALA, and high oleic safflower oil was administered orally to spontaneously hypertensive rats (SHR) of a control and an ALA group on days 1 and 5. Systolic blood pressure was measured on day 1, and blood and liver were collected on day 5. Four hours after the oral administration on day 1, systolic blood pressure of the ALA group was lower than that of the control group. Levels of plasma vasodilators, such as prostaglandin I(2) metabolite, nitric oxide metabolites, and bradykinin, in the ALA group were significantly higher than those in the control group, but levels of vasoconstrictors, such as angiotensin II and thromboxane A(2) metabolite, did not differ significantly. It is known that bradykinin induces prostaglandin I(2) and nitric oxide. The present study shows that ALA reduced the systolic blood pressure of SHR, and its mechanism may be related to increases of prostaglandin I(2) and nitric oxide through bradykinin stimulation.