title: Diabetic HDL-associated myristic acid inhibits acetylcholine-induced nitric oxide generation by preventing the association of endothelial nitric oxide synthase with calmodulin.
abstract: In the current study, we examined whether diabetes affected the ability of HDL to stimulate nitric oxide (NO) production. Using HDL isolated from both diabetic humans and diabetic mouse models, we found that female HDL no longer induced NO synthesis, despite containing equivalent amounts of estrogen as nondiabetic controls. Furthermore, HDL isolated from diabetic females and males prevented acetylcholine-induced stimulation of NO generation. Analyses of both the human and mouse diabetic HDL particles showed that the HDLs contained increased levels of myristic acid. To determine whether myristic acid associated with HDL particles was responsible for the decrease in NO generation, myristic acid was added to HDL isolated from nondiabetic humans and mice. Myristic acid-associated HDL inhibited the generation of NO in a dose-dependent manner. Importantly, diabetic HDL did not alter the levels of endothelial NO synthase or acetylcholine receptors associated with the cells. Surprisingly, diabetic HDL inhibited ionomycin-induced stimulation of NO production without affecting ionomycin-induced increases in intracellular calcium. Further analysis indicated that diabetic HDL prevented calmodulin from interacting with endothelial NO synthase (eNOS) but did not affect the activation of calmodulin kinase or calcium-independent mechanisms for stimulating eNOS. These studies are the first to show that a specific fatty acid associated with HDL inhibits the stimulation of NO generation. These findings have important implications regarding cardiovascular disease in diabetic patients.
authors.affiliation: Department of Pediatrics and Kentucky Pediatric Research Institute, University of Kentucky, Lexington, Kentucky 40536-0230, USA.
authors.forename: James
authors.initials: J
authors.lastname: White
authors.forename: Theresa
authors.initials: T
authors.lastname: Guerin
authors.forename: Hollie
authors.initials: H
authors.lastname: Swanson
authors.forename: Steven
authors.initials: S
authors.lastname: Post
authors.forename: Haining
authors.initials: H
authors.lastname: Zhu
authors.forename: Ming
authors.initials: M
authors.lastname: Gong
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: William V
authors.initials: WV
authors.lastname: Everson
authors.forename: Xiang-An
authors.initials: XA
authors.lastname: Li
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Graf
authors.forename: Hubert O
authors.initials: HO
authors.lastname: Ballard
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Ross
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Smart
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism*; D002478:Cells, Cultured; D003920:Diabetes Mellitus / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D004967:Estrogens / Q000378:metabolism; D005260:Female; D006801:Humans; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D008075:Lipoproteins, HDL / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019814:Myristic Acid / Q000378:metabolism* / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011950:Receptors, Cholinergic / Q000378:metabolism; D054411:Receptors, Leptin / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D002147:Calmodulin; D004967:Estrogens; D007476:Ionophores; D008075:Lipoproteins, HDL; D011950:Receptors, Cholinergic; D054411:Receptors, Leptin; C515447:leptin receptor, mouse; D019814:Myristic Acid; D009569:Nitric Oxide; D015759:Ionomycin; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D000109:Acetylcholine; D002118:Calcium