Actin Cytoskeleton Regulates Stretch-Activated Ca²⁺ Influx in Human Pulmonary Microvascular Endothelial Cells

Abstract

During high tidal volume mechanical ventilation in patients with acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), regions of the lung are exposed to excessive stretch, causing inflammatory responses and further lung damage. In this study, the effects of mechanical stretch on intracellular Ca 21 concentration ([Ca 21 ] i ), which regulates a variety of endothelial properties, were investigated in human pulmonary microvascular endothelial cells (HPMVECs). HPMVECs grown on fibronectin-coated silicon chambers were exposed to uniaxial stretching, using a cell-stretching apparatus. After stretching and subsequent unloading, [Ca 21 ] i , as measured by fura-2 fluorescence, was transiently increased in a strain amplitude-dependent manner.

Stiffness and heterogeneity of the pulmonary endothelial glycocalyx measured by atomic force microscopy

“…The ϽEϾ(␦) results for untreated BLMVECs did not display a sigmoidal shape, so the fitted results were inconclusive. The biomechanical role of cellular structures below the glycocalyx was investigated by treating the cells with cytochalasin D. Cytochalasin D is known to inhibit actin polymerization within the cell, thus causing softening of the cell (18). tions (100 Ͻ ␦ Ͻ 500 nm), for control and enzyme-treated BLMVECs (Figs.…”

A novel bioreactor for the generation of highly aligned 3D skeletal muscle-like constructs through orientation of fibrin via application of static strain

“…However, in terms of expression of structural genes such as TnnT1, a marker for muscle contractility, another potential regulatory mechanism might be strain-induced opening of Ca 2+ channels. It has previously been reported that mechanical stimulation increases intracellular Ca 2+ concentrations in human lung fibroblasts [83], human pulmonary microvascular endothelial cells [84] and neonatal rat myocytes [85] in a transient manner. The transient increase in intracellular Ca 2+ levels shows a similar pattern as observed by Takayama et al after electrical stimulation of C2C12-derived myotubes.…”

Caveolae – mechanosensitive membrane invaginations linked to actin filaments

“…In addition, many ion channels localize to caveolae and several cardiac arrhythmias are related to caveolae malfunction (Balijepalli and Kamp, 2008). Interestingly, stretch-activated Ca 2+ influx through stretch-activated ion channels, some of which are localized in caveolae and/or regulated by caveolins (Gervasio et al, 2008), depends on an intact actin cytoskeleton, which raises the possibility that the association of caveolae with stress fibers might fine-tune these membrane channels (Hayakawa et al, 2008;Ito et al, 2010). A specific role for caveolae, mediated by their ability to flatten out, has recently been demonstrated in the regulation of osmotic swelling activated chloride channel I Cl,swell .…”