12-Hydroxyeicosatetraenoic acid directly potentiates angiotensin II-induced vascular contraction

We studied whether 12-hydroxyeicosatetraenoic acid (HETE) affected the angiotensin II-induced contractile response in isolated hamster aorta. After preincubation with 10 nM 12-HETE for 1, 3, 5, 10 and 30 min, the angiotensin II-induced contractions were increased to 101%, 109%, 114%, 109% and 98%, respectively. The optimum preincubation time for the maximum effect of 12-HETE was 5 min. Under these conditions, 12-HETE increased dose dependently the contraction induced by 10 nM angiotensin II, and the concentration needed for the maximum effect was 30 nM, which increased contraction to 118% compared to the control angiotensin II-induced contraction. We demonstrated clearly that 12-HETE directly potentiates the angiotensin II-induced contraction.