Actin cytoskeleton regulates stretch-activated Ca2+ influx in human pulmonary microvascular endothelial cells

Satoru Ito, Béla Suki, Hiroaki Kume, Yasushi Numaguchi, Masakazu Ishii, Mai Iwaki, Masashi Kondo, Keiji Naruse, Yoshinori Hasegawa, Masahiro Sokabe

Research output: Contribution to journalArticle

47 Citations (Scopus)

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 Ca2+ concentration ([Ca2+]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, [Ca2+] i, as measuredbyfura-2fluorescence,wastransiently increased inastrain amplitude-dependent manner. The elevation of [Ca2+]i induced by stretch was not evident in the Ca2+-free solution and was blocked by Gd31, a stretch-activated channel inhibitor, or ruthenium red, a transient receptor potential vanilloid inhibitor. The disruption of actin polymerization with cytochalasin D inhibited the stretch-induced elevation of [Ca2+]i. In contrast, increases in [Ca2+] i induced by thapsigargin or thrombin were not affected by cytochalasin D. Increased actin polymerization with sphingosine-1-phosphate or jasplakinolide enhanced the stretch-induced elevation of [Ca2+] i. A simple network model of the cytoskeleton was also developed in support of the notion that actin stress fibers are required for efficient force transmission to open stretch-activated Ca2+ channels. In conclusion, mechanical stretch activates Ca2+ influx via stretch-activated channels which are tightly regulated by the actin cytoskeleton differentfrom other Ca2+ influx pathways such as receptor-operated and store-operated Ca2+ entries in HPMVECs. These results suggest that abnormal Ca2+ homeostasis because of excessive mechanical stretch during mechanical ventilation may play a role in the progression of ALI/ARDS.

Original languageEnglish
Pages (from-to)26-34
Number of pages9
JournalAmerican Journal of Respiratory Cell and Molecular Biology
Volume43
Issue number1
DOIs
Publication statusPublished - 01-07-2010

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Pulmonary and Respiratory Medicine
  • Clinical Biochemistry
  • Cell Biology

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