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 (5 mM; 2-DG) plus sodium cyanide (5 mM; 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 2+ ] i (278 ± 24 nM vs. 71 ± 2 nM in the control, n  = 60 cells, P P 2+ ] i response of EC was biphasic with a peak after 1 min (183 ± 6 nM vs. 71 ± 1 nM, n  = 60 cells, P 2+ ] i . A 24-h pre-treatment with 10 mM 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.