Regional differences in intramyocellular lipids in humans observed by in vivo 1H-MR spectroscopic imaging.
Hwang, Jong-Hee, Jullie W. Pan, S. Heydari, Hoby P. Hetherington, and Daniel T. Stein.
Departments of 1Medicine, 2Neurology, and 4Radiology, Albert Einstein College of Medicine, Bronx 10461; and 3Brookhaven National Laboratory, Upton, New York 11973
APStracts 7:0001A, 2000.
Regional differences in the content of intramyocellular lipids (IMCL), extramyocellular lipids, and total creatine (TCr) were quantified in soleus (S), tibialis posterior (TP), and tibialis anterior (TA) muscles in humans using in vivo 1H proton spectroscopic imaging at 4 T. Improved spatial resolution (0.25-ml nominal voxel resolution) made it feasible to measure IMCL in S, TP, and TA simultaneously in vivo. The most significant regional difference was found in the content of IMCL compared with extramyocellular lipids or TCr. The concentrations of TCr were found to be 29-32 mmol/kg, with little regional variation. IMCL content was measured to be 4.8 ± 1.6 mmol/kg tissue wt in S, 2.8 ± 1.3 mmol/kg tissue wt in TP, and 1.6 ± 0.9 mmol/kg tissue wt in TA in the order of S > TP > TA (P < 0.05). It is likely that these IMCL values are consistent with the known fiber types of these muscles, with S having the greatest fraction of type I (slow-twitch, oxidative) fibers and TA having a large fraction of type IIb (fast-twitch, glycolytic) fibers.
Received 22 May 2000; accepted in final form 11 October 2000
APS Manuscript Number A502-0.
Article publication pending J Appl Physiol
ISSN 1080-4757 Copyright 2000 The American Physiological Society.
Published in APStracts on 29 January 2001