TU-F-CAMPUS-I-02: Phosphorus Metabolite Differences Between Type 2 Diabetic and Normal Skeletal Muscle

Authors


Abstract

Purpose:

Type 2 diabetes mellitus (T2DM) is implicated with impaired ATP production in skeletal muscle. Phosphorus-31 magnetic resonance spectroscopy (31P-MRS) was used to measure the baseline concentrations of phosphocreatine (PCr), inorganic phosphate (Pi), and adenosine triphosphate (ATP) in the vastus lateralis (VL) muscle.

Methods:

Six T2DM subjects (6 male, age = 51±12) and three normal glucose tolerant (NGT) subjects (2 male, age = 40±16) were studied. A slice-selective 31P-MRS sequence (TR=10s, TE=2.3 ms, NSA=16, 25mm slice) was performed to determine the absolute concentrations, [PCr], [Pi], [ATP]. After the legs were scanned, a leg phantom (15 cm diameter, 4 L cylinder with 35 mM phosphoric acid (H₃PO₄)), was scanned using the same slab positioning. A 6 mL vial with 850 mM of methylenediphosphonic acid (MDP)) was the external reference standard. The tissue volumes were calculated from a five-slice MRI scan. The jMRUI software package was used to measure the areas under spectral peaks. A two-tailed t-test was performed, with significance deemed as p<0.05.

Results:

The subjects with T2DM had an average absolute [PCr] = 24.9±4.5 mM while for the NGT subjects [PCr] = 31.9±1.9 mM. The t-test showed a significant difference (p=0.04) between the means of the two groups. There was no significant difference between the means for [Pi] and [ATP] between T2DM and NGT subjects. For all nine subjects the average and standard deviation of [Pi] and [ATP] were 2.86±0.45 mM and 6.99±1.30 mM, respectively.

Conclusion:

Subjects with T2DM have lower baseline values of PCr than subjects with normal glucose tolerance. This has not been previously reported and the mechanisms for this need to be studied further. Future studies will investigate the PCr utilization under exercise conditions.

Funding: NIH K Grant 1K25DK089012.

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