title: 12-Hydroxyeicosatetraenoic acid participates in angiotensin II afferent arteriolar vasoconstriction by activating L-type calcium channels.
abstract: The lipoxygenase (LO) metabolite, 12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE], constricts renal vessels, contributes to the vascular response to angiotensin, and has been implicated in cardiovascular and renal diseases. The current studies were performed to determine if renal microvascular 12(S)-HETE production is stimulated by angiotensin and the contribution of L-type calcium channels to the vasoconstriction elicited by 12(S)-HETE. Angiotensin increased renal microvascular 12(S)-HETE production by 64%, whereas cyclooxygenase metabolite production was not altered. Renal microvessels also expressed platelet-type 12-LO and leukocyte-type 12-LO. In the juxtamedullary preparation, afferent arteriolar diameter averaged 21 +/- 1 microm and 12(S)-HETE caused a graded decrease in vessel caliber. The afferent arteriolar response to 12(S)-HETE was abolished during L-type calcium channel inhibition. Renal microvascular smooth muscle cells were studied using fluorescence microscopy. Renal myocyte [Ca2+]i averaged 93 +/- 5 nmol/l. The 12(S)-HETE (5 micromol/l) increased myocyte [Ca2+]i to a peak value of 340 +/- 55 nmol/l. The peak [Ca2+]i response following exposure to 12(S)-HETE was greatly attenuated in the absence of extracellular Ca2+ or calcium channel blockade. These results demonstrate that renal microvascular 12(S)-HETE production is increased in response to angiotensin, and activation of L-type calcium channels is an important mechanism responsible for the afferent arteriolar vasoconstriction elicited by 12(S)-HETE.
authors.affiliation: Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912, USA.
authors.forename: Shih Shen
authors.initials: SS
authors.lastname: Yiu
authors.forename: Xueying
authors.initials: X
authors.lastname: Zhao
authors.forename: Edward W
authors.initials: EW
authors.lastname: Inscho
authors.forename: John D
authors.initials: JD
authors.lastname: Imig
mesh_terms: D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid / Q000096:biosynthesis / Q000494:pharmacology*; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D015220:Calcium Channels / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D015640:Ion Channel Gating / Q000187:drug effects; D007668:Kidney / Q000098:blood supply; D008084:Lipoxygenase / Q000096:biosynthesis; D008297:Male; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction / Q000187:drug effects*
chemical_list: D015220:Calcium Channels; D000804:Angiotensin II; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D008084:Lipoxygenase; D011451:Prostaglandin-Endoperoxide Synthases