13C-NMR study of hypoglycemia-induced glycolytic changes in embryonic mouse heart.
BACKGROUND
Glucose metabolites can be detected in embryonic mouse tissues using 13C-NMR spectroscopy. The advantage of this method is in its chemical specificity and the ability to follow metabolic changes.


METHODS
In this study, CD-1 mice were mated and embryos excised on gestational day (GD) 10.5 (plug = GD 0.5). Hearts were isolated and cultured in 150 mg/dl glucose (normoglycemic medium) or 40 mg/dl glucose (hypoglycemic medium) for 6 hr. 13C-labeled glucose comprised 62%-64% of total glucose in the culture medium. Pre- and postculture media were treated with deuterated water (D2O), and 13C spectra were obtained using a Bruker Avance 500 MHz spectrometer operating at 11.744 tesla (125.7 MHz for 13C). NMR spectra demonstrated resonances for 13C-glucose in preculture normoglycemic and hypoglycemic media. Postculture spectra for normoglycemic and hypoglycemic media demonstrated 13C-glucose signals as well as a signal for 13C-lactate. Area under the curve (AUC) was measured for the [1-(13)C-glucose] resonance from preculture media and the [3-(13)C-lactate] resonance from postculture media. The ratios of AUC for postculture [3-(13)C-lactate] to preculture [1-(13)C-glucose] were calculated and found to be higher in hypoglycemic than in normoglycemic media.


RESULTS
Our results confirm earlier findings using radiolabeled substrates and suggest that 13C-NMR spectroscopy can be used to study glucose metabolism in isolated embryonic hearts exposed to hypoglycemia.


CONCLUSIONS
NMR effectively measures glucose and its metabolite, lactate, in the same spectrum and thus determines metabolic flux in the isolated embryonic heart after exposure to hypoglycemia and normoglycemia. This method could evaluate glucose metabolism in embryonic tissues following other teratogenic exposures.
Ghatnekar
Gautam S
GS
Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina 27606, USA. gsghatne@unity.ncsu.edu
Gracz
Hanna S
HS
Smoak
Ida W
IW
D000818:Animals; D002247:Carbon Isotopes; D003470:Culture Media; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis / Q000502:physiology*; D006321:Heart / Q000196:embryology*; D007003:Hypoglycemia / Q000196:embryology* / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008815:Mice, Inbred Strains; D009206:Myocardium / Q000378:metabolism*; D009924:Organ Culture Techniques
D002247:Carbon Isotopes; D003470:Culture Media; D005947:Glucose