Metabolic effects of interleukin 3 on 32D cl23 cells analyzed by NMR

Abstract

³¹P NMR of living 32D cl23 cells and ¹H NMR of cell extracts were used to study the metabolic effects of interleukin 3 (IL3). When IL3 was removed from 32D cl23 for 9–10 hours ³¹P spectra showed a decrease in sugar phosphate, γATP/ADP, αATP/ADP/NAD, and βATP resonances which declined progressively over a time period of up to 16 hours. By comparison, ATP measurements using the luciferin/luciferase method resulted in the decline of ATP levels from 12 hours in the absence of IL3. At this time, viability of the cells was unaffected. For ¹H NMR experiments cells were grown in the presence and absence of IL3 for 4 and 24 hours, after which acid cell extracts were prepared. These spectra revealed a four-fold decrease in lactate 4 hours post-IL3 removal. Alanine levels were unchanged but glycine was elevated 1.5-fold whilst various other amino acids were elevated slightly. After 24 hours without IL3, only 22% of cells were viable which was reflected in a general decline of most resonance intensities. These findings suggest that IL3 exerts its effect primarily on glucose metabolism and has a delayed secondary effect on maintenance of ATP levels in the cell. We have demonstrated the applicability of high resolution ¹H and ³¹P NMR to the study of cellular metabolism in hemopoietic cells.