Application of a flow-through type pH/CO₂ sensor system based on ISFET for evaluation of the glucose dependency of the metabolic pathways in cultured cells

We have previously reported that a flow-through type pH/CO₂ sensor system using two ion sensitive field effect transistors (ISFETs) could be utilized to evaluate the production rate of total carbonate (secreted CO₂ + secreted bicarbonate ion) and free lactic acid (secreted lactic acid - secreted bicarbonate ion). To validate the usefulness of this system, we applied it to the quantitative analysis of metabolic switching by the change of glucose concentrations in cultured bovine arterial endothelium cell, human umbilical vein endothelium cell and rat cardiac muscle cell. In all of these cell species, a decrease of glucose concentration increased total carbonate that represents the cellular respiration activity and decreased free lactic acid that represents glycolysis activity. We firstly analyzed a switching of metabolic pathways from glycolysis to respiration with a decrease of glucose quantitatively. This ISFET system can be applicable to many biological investigations by analyzing metabolic activity and give dynamic cellular information.