Glucose uptake in mammalian cells measured by ICP-MS

Abstract

We developed a sensitive, ratiometric method to measure simultaneously13C-labeled glucose and rubidium in biological samples using ICP-MS. The method uses probe-assisted ultra-sonication with water to extract 13C-[6C]-labeled-d-glucose and other polar analytes from mammalian tissues. It extracts >80 % of the reference value for Rb and >95 % of 13C in a Certified Reference Material spiked with 13C-[6C]-labeled-d-glucose in the micromolar range. Using optimized instrument conditions, the method achieves a stable 13C/12C signal without spectral interferences. The 13C/12C signal is independent of sample composition and depends linearly on the concentration of 13C-[6C]-labeled-d-glucose in spiked samples. Overall, the method achieves a limit of detection of 60 µM for 6-C-labeled 13C glucose in biological tissues. This detection capability for carbon in biological matrices by ICP-MS opens a wider range of applications for ICP-MS in biomedical research. As proof-of-principle, we combined 13C detection with the multi-channel capability of ICP-MS to measure glucose and rubidium uptake in the same contracting skeletal muscles. Multi-isotope detection is needed to study many biological processes, including coupled membrane transport. These results demonstrate a capability for carbon detection by ICP-MS that can significantly advance studies of complex biological processes that require multi-isotope detection.