Diversity in levels of intracellular total creatine and triglycerides in human skeletal muscles observed by 1H-MRS JESÚS RICO-SANZ,1 E. LOUISE THOMAS,1 GABRIELE JENKINSON,1 ŠÁRKA MIERISOVÁ,2 RICHARD ILES,1 AND JIMMY

Rico-Sanz, Jesús, E. Louise Thomas, Gabriele Jenkinson, Šárka Mierisová, Richard Iles, and Jimmy D. Bell. Diversity in levels of intracellular total creatine and triglycerides in human skeletal muscles observed by 1H-MRS. J. Appl. Physiol. 87(6): 2068–2072, 1999.—We used 1H-magnetic resonance spectroscopy to noninvasively determine total creatine (TCr), choline-containing compounds (Cho), and intracellular (IT) and extracellular (between-muscle fibers) triglycerides (ET) in three human skeletal muscles. Subjects’ (n 5 15 men) TCr concentrations in soleus [Sol; 100.2 6 8.3 (SE) mmol/kg dry wt] were lower (P , 0.05) than those in gastrocnemius (Gast; 125.3 6 9.2 mmol/kg dry wt) and tibialis anterior (TA; 123.7 6 8.8 mmol/kg dry wt). The Cho levels in Sol (35.8 6 3.6 mmol/kg dry wt) and Gast (28.5 6 3.5 mmol/kg dry wt) were higher (P , 0.001 and P , 0.01, respectively) compared with TA (13.6 6 2.4 mmol/kg dry wt). The IT values were found to be 44.8 6 4.6 and 36.5 6 4.2 mmol/kg dry wt in Sol and Gast, respectively. The IT values of TA (24.5 6 4.5 mmol/kg dry wt) were lower than those of Sol (P , 0.01) and Gast (P , 0.05). There were no differences in ET [116.0 6 11.2 (Sol), 119.1 6 18.5 (Gast), and 91.4 6 19.2 mmol/kg dry wt (TA)]. It is proposed that the differences in metabolite levels may be due to the differences in fiber-type composition and deposition of metabolites due to the adaptation of different muscles during locomotion.