Effects of training on the concentration of Na+, K+-ATPase in foal muscle.

Abstract

We investigated the effect of training on the Na+, K+-ATPase concentration in foal skeletal muscle by measurement of [3H]ouabain binding. From the 7th day after birth, 12 foals were divided in 3 groups: a) staying in a box stall (Box); b) staying in a box stall with a training regimen of an increasing number of sprints per day (Training); and c) staying on pasture (Pasture). Euthanasia was performed after 5 months. In semitendinosus muscle, the concentration of [3H]ouabain binding sites (pmol/g wet wt) was 181 +/- 6 in the Box, 220 +/- 15 in the Training, and 197 +/- 8 in the Pasture group (all n = 6; Box vs. Training, P<0.05). In gluteus medius, the concentration of [3H]ouabain binding sites was 168 +/- 9 in the Box, 219 +/- 12 in the Training, and 175 +/- 4 in the Pasture group (all n = 6; Box or Pasture vs. Training, P<0.02). Scatchard analysis of saturation curves showed that the difference in [3H]ouabain binding sites between the 3 groups could not be ascribed to differences in the Kd for ouabain. Both for semitendinosus and gluteus medius muscle, the concentration of [3H]ouabain binding sites increased in the order Box < Pasture < Training (a total increase of around 20%). This suggests a specific effect of the amount and intensity of exercise on the Na+, K+-ATPase concentration in horse skeletal muscle, and may lead to a better performance during exercise.