Stretch-induced mechanical stimulation effects on vascular smooth muscle contractility in aged resistance arteries
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Agerelated impairments of skeletal muscle resistance arteries are associated with alterations in vascular smooth muscle cell (VSMC) contractility. Aerobic exercise is an effective intervention for reversing the impacts of aging on vascular contractility. In addition, we have shown that arterial wall-stretch, induced by a short-duration increase in intraluminal pressure in cannulated soleus muscle feed arteries (SFA), attenuates age-related changes in VSM contractility. The mechanisms responsible for the beneficial effect of wall stretch on contractility are not fully understood. Purpose: VSMC respond to extracellular mechanical signals by dynamic remodeling of actin fibers and cell-matrix adhesions. In this study, we investigated the impact of in vitro cyclic stretch on attenuating the ageinduced alterations in VSMCs contractility by evaluating changes in vinculin, as a marker for cell-matrix adhesions, and smooth muscle -actin (SM-actin) fiber formation. Methods: VSMC isolated from SFA of young (4 month) and old (24 month) male F344 rats were cultured on fibronectinfunctionalized silicon membranes. Equibiaxial cyclic stretch (10%) at 0.25 Hz frequency was applied to both young and old cells for 2 or 5 min. Static condition (no stretch) was used as control. At the end of the study, cells were fixed in their stretched or static state with 2% paraformaldehyde and stained for SM-actin and vinculin. Dual color confocal imaging was performed using Olympus Fluoview 3000 microscope, and SlideBook software was used to analyze the data. Results: Young and old VSMC respond differently to stretch-induced mechanical stimulation. Results showed an increase in actin stress fibers formation in old VSMC for both time points when compared to young cells or old cells at rest. Similarly, vinculin recruitment at cell-matrix adhesion was increased in old VSMC. No differences were found between young and old cells in the static condition for any of the proteins. Conclusion: Taken together, these data show that stretch-induced mechanical stimulation increases actin stress fiber and integrin-based adhesions contributing to improved aged VSM cells contractility. Sydney and J.L. Huffines Institute for Sports Medicine and Human Performance This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
