title: Ca2+ ATPase in Dutch warmblood foals compared with Na+, K+ ATPase: intermuscular differences and the effect of exercise.
abstract: We studied the effects of exercise without or with a subsequent period on pasture on Ca2+ ATPase concentration in foal skeletal muscle, and compared the results with those previously reported on Na+, K+ ATPase. Ca2+ ATPase was measured in homogenates as Ca2+-dependent steady-state phosphorylation from [gamma-32P]ATP. From day 7 after birth, 24 foals were divided into three groups: (i) staying in a box stall (Box); (ii) staying in a box stall with an exercise programme of an increasing number of sprints per day (Exercise); and (iii) staying on pasture (Pasture). Half of the foals (12 with four in each treatment group) were killed after 5 months. The remaining foals stayed on pasture until 11 months. In the 5-month Pasture group, Ca2+ ATPase concentration was 29.4 +/- 4.3 nmol/g wet weight (wt) (n = 4) in gluteus medius muscle, 25.2 +/- 3.3 nmol/g wet wt (n = 4) in semitendinosus muscle (both mixed fibre type), and 4.1 +/- 1.7 nmol/g wet wt (n = 3) in the slow masseter muscle. These values were not altered by exercise or by box rest. This was in contrast to the Na+, K+ ATPase concentration which was not different between the three muscles, but showed a 20% rise in gluteus medius and semitendinosus muscle after exercise. In the period from 5 to 11 months on pasture, there was no change in Ca2+ ATPase in any group. In conclusion, the Ca2+ ATPase concentration in foal muscle is around 6-fold higher in mixed fibres than in slow fibres. Furthermore, the enzyme is not up- or down-regulated by sprint exercise or subsequent rest.
authors: Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, PO Box 80.158, 3508 TD Utrecht, The Netherlands.
authors: P
authors: P
authors: Suwannachot
authors: C B
authors: CB
authors: Verkleij
authors: P R
authors: PR
authors: Van Weeren
authors: M E
authors: ME
authors: Everts
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D006736:Horses / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000201:enzymology* / Q000254:growth & development; D010805:Physical Conditioning, Animal / Q000502:physiology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
chemical_list: D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase