Smooth Muscle Contractile Plasticity in Rat Mesenteric Small Arteries: Sensitivity to Specific Vasoconstrictors, Distension and Inflammatory Cytokines

Abstract

Small artery remodeling may involve a shift in the diameter-dependent force generating capacity of smooth muscle cells (SMC). We tested to what extent and under which conditions such contractile plasticity occurs. Rat mesenteric arteries were mounted on isometric myographs. Active diameter-tension relations were determined after application of several stimuli for 16 or 40 h at 40 or 110% of the passive diameter at 100 mm Hg. At 40%, 16-hour incubation with endothelin-1 (ET-1) but not U46619 shifted force capacity towards smaller diameters. Inflammatory cytokines (TNF-α, IL-1β, IFN-γ), TGF-β or serum neither induced such shift nor augmented the effect of ET-1. The ET-1-mediated change was not affected by superoxide dismutase and catalase. Inward matrix remodeling in the presence of ET-1 was slower, occurring after 40 h. Arteries maintained at 110% showed a shift of force capacity to larger diameters, which was prevented by ET-1 but not by U46619. In the active but not the passive state, SMC had altered nuclear lengths after incubation at 40%. These data demonstrate contractile plasticity in small arteries, where chronic strain is an outward drive and specifically ET-1 an inward drive, acting through mechanisms that do not seem to relate to oxidative stress, inflammatory pathways or major reorganization of the SMC.