Background: Endothelial barrier dysfunction (EBD) involves microtubule disassembly and enhanced cell contractility. Histone deacetylase 6 (HDAC6) deacetylates alpha-tubulin, and thereby destabilizes microtubules. This study investigates a role for HDAC6 in EBD. Methods: EBD was induced with thrombin +/- HDAC6 inhibitors (tubacin and MC1575), and assessed by transendothelial electrical resistance (TEER). Markers for microtubule disassembly (alpha-tubulin and acetylated alpha-tubulin) and contraction (phosphorylated myosin light chain 2, P-MLC2) were measured using immunoblots and immunofluorescence. Results and conclusion: Thrombin induced a similar to 50% decrease in TEER that was abrogated by the HDAC6 inhibitors. Moreover, inhibition of HDAC6 diminished edema in the lung injured by lipopolysaccharide. Lastly, inhibition of HDAC6 attenuated thrombin-induced microtubule disassembly and P-MLC2. Our results suggest that HDAC6 can be targeted to limit EBD. (C) 2011 Elsevier Inc. All rights reserved.