title: Preservation of sarcoplasmic reticulum Ca2(+)-sequestering function in homogenates of different type composition following sprint activity.
abstract: To examine the effect of exercise on sarcoplasmic reticulum function in muscle tissue of different fibre composition, adult male Wistar rats weighing 388 +/- 23 g (x +/- SE) ran intermittently on a treadmill until fatigue. Fatigue was induced by 15-20 min of running performed at 52 m/min on an 8 degrees incline in periods of 2.5 min of exercise separated by 2 min of recovery. Analysis of sarcoplasmic reticulum Ca2+ ATPase activity determined in homogenates indicated no difference (p > 0.05) between age-matched control and exercised tissue for the soleus (SOL; 0.121 +/- 0.012 vs. 0.156 +/- 0.018 mumol.mg-1 protein.min-1), red gastrocnemius (RG; 0.381 +/- 0.022 vs. 0.354 +/- 0.022), or white gastrocnemius (WG; 0.526 +/- 0.05 vs. 0.471 +/- 0.031). Similarly, both total ATPase and Mg2+ ATPase activities were unaffected by the exercise in any of the tissues examined. Exercise also failed to alter sarcoplasmic reticulum Ca2+ uptake in homogenates of the SOL (1.43 +/- 0.15 vs. 1.38 +/- 0.19 nmol.mg-1 protein.min-1), RG (3.74 +/- 0.29 vs. 3.59 +/- 0.24), and WG (5.98 +/- 0.48 vs. 5.41 +/- 0.50). At fatigue, glycogen depletion was similar in all tissue types and amounted to 65.1% in the SOL (172 +/- 9 vs. 60 +/- 16 mmol.glucosyl units-1.kg-1 dry weight), 74.4% in RG (164 +/- 8 vs. 42 +/- 6), and 79% in the WG (167 +/- 9 vs. 35 +/- 9). It is concluded that exercise by itself does not alter sarcoplasmic reticulum Ca2(+)-sequestering function in tissues of primarily different fibre composition when determined in homogenates in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Kinesiology, University of Waterloo, ON, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Dossett-Mercer
authors.forename: H J
authors.initials: HJ
authors.lastname: Green
authors.forename: E
authors.initials: E
authors.lastname: Chin
authors.forename: F
authors.initials: F
authors.lastname: Grange
mesh_terms: D000251:Adenosine Triphosphatases / Q000032:analysis; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000032:analysis*; D003401:Creatine / Q000032:analysis; D006003:Glycogen / Q000032:analysis; D066298:In Vitro Techniques; D007773:Lactates / Q000032:analysis; D019344:Lactic Acid; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D009711:Nucleotides / Q000032:analysis; D010710:Phosphates / Q000032:analysis; D005082:Physical Exertion / Q000502:physiology; D011773:Pyruvates / Q000032:analysis; D019289:Pyruvic Acid; D051381:Rats; D017208:Rats, Wistar; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*
chemical_list: D007773:Lactates; D009711:Nucleotides; D010710:Phosphates; D011773:Pyruvates; D019344:Lactic Acid; D019289:Pyruvic Acid; D006003:Glycogen; D000251:Adenosine Triphosphatases; D000252:Calcium-Transporting ATPases; D003401:Creatine; D002118:Calcium