Modulation of vascular tone by 12(R)-, but not 12(S)-, hydroxyeicosatetraenoic acid.

The vascular activity of the two stereoisomers of 12-hydroxyeicosatetraenoic acid (12-HETE) was assessed on rabbit thoracic aortic rings. In vessels contracted in K+-free media, 12(R)-HETE inhibited the relaxations produced by the addition of KCl, in a concentration-dependent manner, while 12(S)-HETE had little effect. 12(R)-HETE, but not the 12(S) isomer, potentiated phenylephrine-induced contractions of aortic rings in normal buffer. Thus 12(R)-HETE can modulate vascular tone, perhaps by inhibition of Na+,K+-ATPase activity.