Flow (shear stress)-induced endothelium-dependent dilation is altered in mice lacking the gene encoding for dystrophin.
BACKGROUND
Dystrophin has a key role in striated muscle mechanotransduction of physical forces. Although cytoskeletal elements play a major role in the mechanotransduction of pressure and flow in vascular cells, the role of dystrophin in vascular function has not yet been investigated. Thus, we studied endothelial and muscular responses of arteries isolated from mice lacking dystrophin (mdx mice).


RESULTS
Carotid and mesenteric resistance arteries 120 micrometer in diameter were isolated and mounted in vitro in an arteriograph to control intraluminal pressure and flow. Blood pressure was not affected by the absence of dystrophin. Pressure-induced (myogenic), phenylephrine-induced, and KCl-induced forms of tone were unchanged. Flow (shear stress)-induced dilation in arteries isolated from mdx mice was decreased by 50% to 60%, whereas dilation to acetylcholine or sodium nitroprusside was unaffected. NG-nitro-L-arginine methyl ester-sensitive flow dilation was also decreased in arteries from mdx mice. Thus, the absence of dystrophin was associated with a defect in signal transduction of shear stress. Dystrophin was present in vascular endothelial and smooth muscle cells, as shown by immunolocalization, and localized at the level of the plasma membrane, as seen by confocal microscopy of perfused isolated arteries.


CONCLUSIONS
-This is the first functional study of arteries lacking the gene for dystrophin. Vascular reactivity was normal, with the exception of flow-induced dilation. Thus, dystrophin could play a specific role in shear-stress mechanotransduction in arterial endothelial cells. Organ damage in such diseases as Duchenne dystrophy might be aggravated by such a defective arterial response to flow.
Loufrani
L
L
Institut National de la Santé et de la Recherche Médicale (INSERM) U 541, IFR6, Université Paris VII, France.
Matrougui
K
K
Gorny
D
D
Duriez
M
M
Blanc
I
I
Lévy
B I
BI
Henrion
D
D
D000109:Acetylcholine / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002118:Calcium / Q000494:pharmacology; D002339:Carotid Arteries / Q000187:drug effects / Q000378:metabolism; D016189:Dystrophin / Q000032:analysis / Q000172:deficiency* / Q000235:genetics; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D008638:Mesenteric Arteries / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D018101:Mice, Inbred mdx; D018613:Microscopy, Confocal; D018482:Muscle, Skeletal / Q000098:blood supply / Q000187:drug effects / Q000502:physiology*; D009599:Nitroprusside / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D015398:Signal Transduction; D014664:Vasodilation / Q000187:drug effects
D016189:Dystrophin; D009599:Nitroprusside; D010656:Phenylephrine; D011189:Potassium Chloride; D000109:Acetylcholine; D002118:Calcium