Background: Arteries chronically constricted in culture remodel to smaller diameters. Conversely, elevated luminal shear stress (SS) promotes outward remodeling of arteries in vivo and prevents inward remodeling in culture in… Click to show full abstract
Background: Arteries chronically constricted in culture remodel to smaller diameters. Conversely, elevated luminal shear stress (SS) promotes outward remodeling of arteries in vivo and prevents inward remodeling in culture in a nitric oxide synthase (NOS)-dependent manner. Objectives: To determine whether SS-induced prevention of inward remodeling in cultured arteries is specifically eNOS-dependent and requires dilation, and whether SS alters the expression of eNOS and other genes potentially involved in remodeling. Methods: Female mouse thoracodorsal arteries were cannulated, pressurized to 80 mm Hg, and cultured for 2 days with low SS (<7 dyn/cm2), high SS (≥15 dyn/cm2), high SS + L-NAME (NOS inhibitor, 10–4 M), or high SS in arteries from eNOS–/– mice. In separate arteries cultured 1 day with low or high SS, eNOS and connexin (Cx) 37, Cx40, and Cx43 mRNA were assessed with real-time PCR. Results: High SS caused little change in passive diameters after culture (–4.7 ± 2.0%), which was less than low SS (–18.9 ± 1.4%; p < 0.0001), high SS eNOS–/– (–18.0 ± 1.5; p < 0.001), or high SS + L-NAME (–12.0 ± 0.6%; nonsignificant) despite similar constriction during culture. Cx37 mRNA expression was increased (p < 0.05) with high SS, but other gene levels were not different. Conclusions: eNOS is involved in SS-induced prevention of inward remodeling in cultured small arteries. This effect does not require NO-mediated dilation. SS increased Cx37.
               
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