Intracellular calcium and pH alterations induced by Escherichia coli endotoxin in rat hepatocytes

Abstract

In this study, the fluorescent Ca2+ probe fura-2 and the fluorescent pH indicator BCECF have been used to monitor cytosolic free Ca2+ and intracellular pH (pHi), respectively, in isolated and cultured hepatocytes treated with Escherichia coli O111:B4 endotoxin. Uptake of 45Ca2+ was also measured to study the effect of endotoxin on the extracellular calcium influx. Endotoxin treatment produced a progressive increase of cytosolic Ca2+ in a dose-dependent manner caused by both induction of a significant release of Ca2+ from intracellular stores and stimulation of the extracellular calcium influx. The perturbation of Ca2+ homeostasis by endotoxin may cause an abnormal stimulation of physiological processes, developing lethal cell injury. Endotoxin also produced a significant decrease in the pHi of hepatocytes which can justify important metabolic alterations during endotoxicosis.