Magnetic resonance imaging of isolated skeletal muscles. Osmotic influence.
OBJECTIVE
The authors evaluate the contribution of intracellular water to the change of T2 relaxation time.


METHODS
Magnetic resonance images of frog muscles (n = 16) were obtained in hypotonic, isotonic, and hypertonic solutions, and their leg weights and T2 relaxation times were measured. Likewise, these values were measured after electric stimulation for 2 to 10 minutes in isotonic solution (n = 5).


RESULTS
The muscle weights increased in the hypotonic solutions, whereas they showed no change in isotonic solution. T2 relaxation times, however, showed little change in either isotonic or hypotonic solutions. In electrically stimulated muscles, T2 relaxation times increased, accompanying the increase in muscle weight in isotonic solutions.


CONCLUSIONS
Muscle contraction results in increased T2 relaxation time, but intracellular water hardly contributes to the increase in this value. Therefore, an increase in extracellular water may be the main cause of the increase in T2 relaxation time seen in exercised muscles.
Yoshioka
H
H
Division of Radiation Medicine, National Institute of Radiological Sciences, Chiba, Japan.
Itai
Y
Y
D000818:Animals; D001001:Anura; D001834:Body Water / Q000502:physiology; D004558:Electric Stimulation; D006982:Hypertonic Solutions; D007038:Hypotonic Solutions; D066298:In Vitro Techniques; D007552:Isotonic Solutions; D008279:Magnetic Resonance Imaging; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000502:physiology; D011930:Reaction Time
D006982:Hypertonic Solutions; D007038:Hypotonic Solutions; D007552:Isotonic Solutions