title: Lithium prevents early cytosolic calcium increase and secondary injurious calcium overload in glycolytically inhibited endothelial cells.
abstract: Cytosolic free calcium concentration ([Ca(2+)]i) is a central signalling element for the maintenance of endothelial barrier function. Under physiological conditions, it is controlled within narrow limits. Metabolic inhibition during ischemia/reperfusion, however, induces [Ca(2+)]i overload, which results in barrier failure. In a model of cultured porcine aortic endothelial monolayers (EC), we addressed the question of whether [Ca(2+)]i overload can be prevented by lithium treatment. [Ca(2+)]i and ATP were analysed using Fura-2 and HPLC, respectively. The combined inhibition of glycolytic and mitochondrial ATP synthesis by 2-desoxy-d-glucose (5mM; 2-DG) plus sodium cyanide (5mM; NaCN) caused a significant decrease in cellular ATP content (14±1 nmol/mg protein vs. 18±1 nmol/mg protein in the control, n=6 culture dishes, P<0.05), an increase in [Ca(2+)]i (278±24 nM vs. 71±2 nM in the control, n=60 cells, P<0.05), and the formation of gaps between adjacent EC. These observations indicate that there is impaired barrier function at an early state of metabolic inhibition. Glycolytic inhibition alone by 10mM 2-DG led to a similar decrease in ATP content (14±2 nmol/mg vs. 18±1 nmol/mg in the control, P<0.05) with a delay of 5 min. The [Ca(2+)]i response of EC was biphasic with a peak after 1 min (183±6 nM vs. 71±1 nM, n=60 cells, P<0.05) followed by a sustained increase in [Ca(2+)]i. A 24-h pre-treatment with 10mM of lithium chloride before the inhibition of ATP synthesis abolished both phases of the 2-DG-induced [Ca(2+)]i increase. This effect was not observed when lithium chloride was added simultaneously with 2-DG. We conclude that lithium chloride abolishes the injurious [Ca(2+)]i overload in EC and that this most likely occurs by preventing inositol 3-phosphate-sensitive Ca(2+)-release from the endoplasmic reticulum. Though further research is needed, these findings provide a novel option for therapeutic strategies to protect the endothelium against imminent barrier failure.
authors.affiliation: Department of Neurology, University of Duisburg-Essen, Germany. bert.bosche@uk-essen.de
authors.forename: Bert
authors.initials: B
authors.lastname: Bosche
authors.forename: Matthias
authors.initials: M
authors.lastname: Schäfer
authors.forename: Rudolf
authors.initials: R
authors.lastname: Graf
authors.forename: Frauke V
authors.initials: FV
authors.lastname: Härtel
authors.forename: Ute
authors.initials: U
authors.lastname: Schäfer
authors.forename: Thomas
authors.initials: T
authors.lastname: Noll
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001011:Aorta / Q000166:cytology; D002118:Calcium / Q000009:adverse effects / Q000378:metabolism*; D020013:Calcium Signaling; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism*; D003847:Deoxyglucose / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D016257:Fura-2; D006019:Glycolysis / Q000187:drug effects*; D008094:Lithium / Q000494:pharmacology / Q000627:therapeutic use; D018021:Lithium Chloride / Q000378:metabolism / Q000494:pharmacology*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D013552:Swine; D013997:Time Factors
chemical_list: D000255:Adenosine Triphosphate; D008094:Lithium; D003847:Deoxyglucose; D018021:Lithium Chloride; D002118:Calcium; D016257:Fura-2