Accession Number : ADA265309


Title :   Effect of Intermittent Cold Exposure on the Fiber-Type Composition of Selected Skeletal Muscles in Rats


Descriptive Note : Final technical rept. Mar-Nov 1990


Corporate Author : ARMSTRONG LAB BROOKS AFB TX


Personal Author(s) : Walters, Thomas J ; Constable, Stefan H


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a265309.pdf


Report Date : Apr 1993


Pagination or Media Count : 13


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.


Descriptors :   *MUSCLES , *MUSCULOSKELETAL SYSTEM , *EXPOSURE(PHYSIOLOGY) , CONTROL , TEMPERATURE , LOW TEMPERATURE , SYNTHASES , COLD WATER , PH FACTOR , MYOSIN , MITOCHONDRIA , THYROID HORMONES , COLD TOLERANCE , LABORATORY ANIMALS , TRANSFORMATIONS , HYPOTHERMIA , DEEP WATER , RESPONSE(BIOLOGY) , RATS , ENZYMES , METABOLISM , REDUCTION


Subject Categories : Anatomy and Physiology
      Stress Physiology


Distribution Statement : APPROVED FOR PUBLIC RELEASE