Effect of Intermittent Cold Exposure on the Fiber-Type Composition of Selected Skeletal Muscles in Rats
Abstract
We examined the effect of long-term intermittent cold exposure (CE) on the fiber-type composition of the predominantly type I soleus and the predominantly type IIb extensor digitorum longus (EDL) muscles of the rats. CE was accomplished by submerging the rats in shoulder-deep water, maintained at 20 = 0.5 deg C, for 1 h/d, 5 d/wk, for up to 19 weeks. Rats were randomly assigned to either a Control (CON) or Cold Exposure group. The efficacy of the treatment was tested by subjecting both groups to 20 deg C water for 45 minutes while measuring rectal temperature (Tre) and V02. The CE group displayed a 22% smaller reduction in Tre (p < 0.05) at the end of the exposure, and had a 23% greater V02 (P < 0-05) during the same period. Fiber-type composition was determined using routine histochemical methods for myosin-ATPase. The soleus muscle of the CE rats underwent a 156% increase in the number of type IIa fibers (p < 0.05), with a 24% reduction in type I fibers (p < 0.05). CE had no significant influence on the fiber-type composition of the EDL muscle. CE resulted in an increase in citrate synthase activity of 20% and 22% in the soleus and EDL muscles, respectively (p < 0.05). The present study demonstrates that intermittent CE induces a type I-to-type IIa transformation in the soleus muscle while having no influence on the EDL muscle.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1993
- Accession Number
- ADA265309
Entities
People
- Stefan H. Constable
- Thomas J. Walters
Organizations
- Armstrong Laboratory