Monitoring carnosine uptake by RAW 264.7 macrophage cells using microchip electrophoresis with fluorescence detection

In this report, a microchip electrophoresis system with fluorescence detection was used for the quantitation of intracellular carnosine in untreated and stimulated macrophage cell lysates. Carnosine was derivatized with NDA/CN and separated from other endogenous amine reported in macrophage cells. Based on ME-LIF with standard addition, macrophages were estimated to contain a basal intracellular concentration of carnosine (0.079 ± 0.02 nmol per million cells). Carnosine is readily taken up by macrophages in cell culture. Incubation with 20 mM carnosine led to a 600-fold increase in intracellular carnosine compared to basal levels. Furthermore, we have shown that under pro-inflammatory conditions using LPS and IFN-gamma stimulation there is a further 3-fold increase in carnosine uptake in macrophage cells. This suggests that there is a mechanism through which macrophages increase the usage of carnosine during oxidative stress.