Vasoactive agonists induce oscillatory changes in vascular smooth muscle cell stiffness and alter cytoskeletal architecture

Abstract

Vasoactive agonists induce coordinated and simultaneous changes in vascular smooth muscle cell (VSMC) stiffness and integrin adhesion. In this study we analyzed the dynamic effects of vasoactive agonists on VSMC stiffness and cortical cytoskeletal structure. Real‐time measurement of cell stiffness was obtained with atomic force microscopy (AFM) and analyzed with Eigen decomposition. Stiffness in VSMCs displayed temporal oscillations with three components at 0.001, 0.004, and 0.007 Hz frequency. The vasoconstrictor angiotensin II (ANG II, 10−6M) increased the amplitude of these oscillations (+100%) whereas adenosine (ADO, 10−4M), a vasodilator, had the opposite effects (−50%). To examine whether alterations in cortical cytoskeletal structure was part of these effects, AFM was used to image VSMC topography before and after treatment with ANG II or ADO. Topographical AFM images revealed the distribution and orientation of cytoskeletal stress fibers. Analysis with Matlab showed that ANG II increased the parallel alignment, density and thickness of the cortical stress fibers. In contrast, ADO showed reverse effects on the stress fibers. These findings demonstrate that the vasoactive agonists dynamically alter temporal behavior and structure of the VSMC cytoskeleton and may play an important role in contributing to the normal contractile behavior of VSMC. (1P01HL095486 to G.A.M. and AHA 0835676N to Z.S.)