title: Influence of exercise training and exhaustion on 45Ca++ content of skeletal muscle mitochondria and fragmented sarcoplasmic reticulum.
abstract: Following a 25 muCi/Kg i/p. injection, 45Ca++ activity from the mitochondria and fragmented sarcoplasmic reticulum (FSR) of the superficial rectus femoris (FG-fibers) and combined soleus muscle (SO-fibers) of trained (T, N = 9) and untrained (UT, N = 8) male Wistar rats was determined. The FG mitochondrial 45Ca++ activity from rested animals was 3.9 (T) and 5.3 (UT) times greater than the FSR from this muscle group while the so-mitochondrial 45Ca++ activity was 13.2 (T) and 20.5 (UT) times greater when compared with the respective SO-FSR (p less than .01). The mitochondrial 45Ca++ content of the SO-fibers from rested animals was 58% UT, p less than .01) and 148% (T, p less than .001) greater than that of the FG mitochondria. After 20-26 weeks of exercise training the SO-mitochondrial 45Ca++ content of the rested-T animals was approximately 18% lower (p less than .05) while the T-FG-mitochondrial 45Ca++ content was 48% less than that of UT animals (p less than .01) with a concomitant 28% greater 45Ca++ activity in SO-FSR for the T-group as compared to UT (p less than .01). Following a rapidly exhaustive treadmill run the mitochondrial 45Ca++ content in the UT group was depressed by 21% in SO-fibers and 37% in FG-fibers (p less than .01) with no changes occurring in the T-group. Exhaustion produced no significant changes in the 45Ca++ activity of the FSR from either group of animals.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D006019:Glycolysis; D066298:In Vitro Techniques; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism*; D010084:Oxidation-Reduction; D005082:Physical Exertion; D051381:Rats; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*
chemical_list: D002132:Calcium Radioisotopes; D002118:Calcium