Effects of type 1 diabetes, sprint training and sex on skeletal muscle sarcoplasmic reticulum Ca2+ uptake and Ca2+-ATPase activity
Calcium cycling is integral to muscle performance during the rapid muscle contraction and relaxation of high-intensity exercise. Ca(2+) handling is altered by diabetes mellitus, but has not previously been investigated in human skeletal muscle. We investigated effects of high-intensity exercise and sprint training on skeletal muscle Ca(2+) regulation among men and women with type 1 diabetes (T1D, n = 8, 3F, 5M) and matched non-diabetic controls (CON, n = 8, 3F, 5M). Secondarily, we examined sex differences in Ca(2+) regulation. Subjects undertook 7 weeks of three times-weekly cycle sprint training. Before and after training, performance was measured, and blood and muscle were sampled at rest and after high-intensity exercise. In T1D, higher Ca(2+)-ATPase activity (+28%) and Ca(2+) uptake (+21%) than in CON were evident across both times and days (P < 0.05), but performance was similar. In T1D, resting Ca(2+)-ATPase activity correlated with work performed until exhaustion (r = 0.7, P < 0.01). Ca(2+)-ATPase activity, but not Ca(2+) uptake, was lower (-24%, P < 0.05) among the women across both times and days. Intense exercise did not alter Ca(2+)-ATPase activity in T1D or CON. However, sex differences were evident: Ca(2+)-ATPase was reduced with exercise among men but increased among women across both days (time x sex interaction, P < 0.05). Sprint training reduced Ca(2+)-ATPase (-8%, P < 0.05), but not Ca(2+) uptake, in T1D and CON. In summary, skeletal muscle Ca(2+) resequestration capacity was increased in T1D, but performance was not greater than CON. Sprint training reduced Ca(2+)-ATPase in T1D and CON. Sex differences in Ca(2+)-ATPase activity were evident and may be linked with fibre type proportion differences.
|ISBN||1469-7793 (Electronic) 0022-3751 (Linking)|
|Authors||Harmer, A. R.; Ruell, P. A.; Hunter, S. K.; McKenna, M. J.; Thom, J. M.; Chisholm, D. J.; Flack, J. R.;|
|Publisher Name||JOURNAL OF PHYSIOLOGY-LONDON|
|Published Issue||Pt 3|
|URL link to publisher's version||http://www.ncbi.nlm.nih.gov/pubmed/24297852|
|OpenAccess link to author's accepted manuscript version||https://publications.gimr.garvan.org.au/open-access/12667|