Azilsartan, an angiotensin II type 1 receptor blocker, restores endothelial function by reducing vascular inflammation and by increasing the phosphorylation ratio Ser(1177)/Thr(497) of endothelial nitric oxide synthase in diabetic mice.
BACKGROUND
Azilsartan, an angiotensin II type 1 (AT1) receptor blocker (ARB), has a higher affinity for and slower dissociation from AT1 receptors and shows stronger inverse agonism compared to other ARBs. Possible benefits of azilsartan in diabetic vascular dysfunction have not been established.


METHODS
We measured vascular reactivity of aortic rings in male KKAy diabetic mice treated with vehicle, 0.005% azilsartan, or 0.005% candesartan cilexetil for 3 weeks. Expression of markers of inflammation and oxidative stress was measured using semiquantitative RT-PCR in the vascular wall, perivascular fat, and skeletal muscle. Phosphorylation of endothelial nitric oxide synthase (eNOS) at Ser1177 and Thr495 was measured using Western blotting, and the ratio of phosphorylation at Ser1177 to phosphorylation at Thr495 was used as a putative indicator of vascular eNOS activity.


RESULTS
(1) Vascular endothelium-dependent relaxation with acetylcholine in KKAy mice was improved by azilsartan treatment compared to candesartan cilexetil; (2) the ratio of Ser1177/Thr495 phosphorylation of eNOS was impaired in KKAy and was effectively restored by azilsartan; (3) anomalies in the expression levels of monocyte chemotactic protein 1 (MCP1), F4/80, NAD(P)H oxidase (Nox) 2, and Nox4 of the aortic wall and in the expression of TNFα in the perivascular fat were strongly attenuated by azilsartan compared to candesartan cilexetil.


CONCLUSIONS
These results provide evidence that azilsartan prevents endothelial dysfunction in diabetic mice, more potently than does candesartan cilexetil. Azilsartan's higher affinity for and slower dissociation from AT1 receptors may underlie its efficacy in diabetic vascular dysfunction via a dual effect on uncoupled eNOS and on Nox.
Sachiko
S
Matsumoto
Department of Cardio-Diabetes Medicine, The University of Tokushima Graduate School of Health Biosciences, 3-18-15 Kuramoto, Tokushima 770-8503, Japan. mshimabukuro-ur@umin.ac.jp.
Michio
M
Shimabukuro
Daiju
D
Fukuda
Takeshi
T
Soeki
Ken
K
Yamakawa
Hiroaki
H
Masuzaki
Masataka
M
Sata
D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology / Q000627:therapeutic use*; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D009924:Organ Culture Techniques; D010069:Oxadiazoles / Q000494:pharmacology / Q000627:therapeutic use*; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D012694:Serine / Q000378:metabolism; D013912:Threonine / Q000378:metabolism; D014657:Vasculitis / Q000188:drug therapy / Q000378:metabolism*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
D047228:Angiotensin II Type 1 Receptor Blockers; D001562:Benzimidazoles; D010069:Oxadiazoles; D013912:Threonine; D012694:Serine; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; C521273:azilsartan