© 2003 by European Society of Cardiology
Copyright © 2003, European Society of Cardiology
Inhibition of contractile activation reduces reoxygenation-induced endothelial gap formation
Institute of Physiology, Justus-Liebig-University Giessen, Aulweg 129, D-35392 Giessen, Germany
* Corresponding author. Tel.: +49-641-99-47241; fax: +49-641-99-47239. michael.piper{at}physiologie.med.uni-giessen.de
Objective: Barrier function of coronary endothelium becomes disturbed by ischemia–reperfusion. We investigated the mechanism of reperfusion-induced endothelial gap formation in monolayers of cultured endothelial cells (CEC) of the rat, exposed to simulated ischemia (40 min anoxia, pHo 6.4) and reperfusion (30 min reoxygenation, pHo 7.4). Methods: Cytosolic Ca2+ (fura-2) and intercellular gap formation (planimetrical analysis) were determined. Reoxygenation conditions were varied: (a) continuing perfusion at pHo 6.4, (b) with or without glucose (2.5 mM), (c) in presence of NaCN (2 mM), (d) with Ca2+ (10 mM) or BAPTA/AM (25 µM), (e) in the presence of myosin light chain kinase inhibitors ML-7 (5 µM) or wortmannin (1 µM). Results: During anoxia, CEC developed cytosolic Ca2+ overload which was not reversed during 30 min reoxygenation. Intercellular gap formation started during anoxia, but was increased during reoxygenation. Reoxygenation-related gap formation was largest in presence of glucose, lower when glucose was withdrawn or NaCN was added. Presence of ML-7 or wortmannin also reduced gap formation during reoxygenation. Conclusions: Reoxygenation induces gap formation. This is dependent on (i) Ca2+ overload during reoxygenation, (ii) energy production and (iii) activation of myosin light chain kinase. Together these results indicate that activation of the endothelial contractile machinery is the underlying cause.
KEYWORDS Calcium (cellular); Contractile apparatus; Endothelial function; Ischemia; Reperfusion
* The review process and the Editorial decision was the responsibility of the previous Editorial team.