Lactate-transport activity in RBCs of trained and untrained individuals from four racing species

Abstract

In red blood cells (RBC) of horses, both lactate-transport activity and lactate accumulation during races vary interindividually. To study whether similar variation in lactate transport is apparent also in RBCs of other racing species, blood samples were collected from 21 reindeer, 40 horses, 31 humans, and 38 dogs. Total lactate-transport activity was measured at 10 and 30 mM concentrations, and the roles of the monocarboxylate-transporter (MCT) and the inorganic anion-exchange transporter (band-3 protein) were studied with inhibitors. In the reindeer and in one-third of the horses, lactate transport was low and mediated mainly by band-3 protein and nonionic diffusion. In the humans, dogs, and the remaining two-thirds of the horses, lactate transport was high and MCT was the main transporter. No correlation existed between MCT activity and the athleticism of the species. In the horses and humans, training had no effect on lactate transport, but in the reindeer and sled dogs, training increased total lactate transport. These results show that among the racing species studied, only in horses was the distribution of lactate-transport activity bimodal, and the possible connection between RBC lactate and performance capacity, especially in this species, warrants further studies.

Age‐related changes and inheritance of lactate transport activity in red blood cells

“…Because the levels of thyroid hormones in foals are higher than in mature horses ( 1981), the high MCT activity in the former could be related to high concentrations of thyroid hormones, and the decrease in MCT activity with age could be due to a decrease in the concentration of these hormones. We have earlier concluded that, in horses, training has no effect on lactate transport activity (Väihkönen and Pösö 1998;Väihkönen et al 2001). However, in our earlier study (Väihkönen and Pösö 1998), horses in the different age groups were not the same individuals.…”

“…Of these horses, 43 belonged to the 51 horses also used in the repeatability study. The data from the 15 dams were included in a sedentary control group in our previous study (Väihkönen et al 2001). The repeatability study also includes some horses from which data (one sample from each horse) has been presented in an earlier study (Väihkönen and Pösö 1998).…”

“…Based on the results from previous studies (Väihkönen and Pösö 1998;Väihkönen et al 1999Väihkönen et al , 2001), horses were classified into 2 groups based on their lactate transport activity (nmol/mg x min) measured at 10 mmol/l lactate concentration; low (LT) activity with ≤ 1 and high (HT) activity with >1. In the sample, 24 of the 101 horses (24%) were classified as LT.…”

“…The main lactate carriers on the RBC membrane are the H + -monocarboxylate cotransporter (MCT) and the anion-exchange protein (AE1) (Poole and Halestrap 1993;Juel 1998). We have shown previously that, in Standardbred horses, lactate transport activity varies between individuals and, based on this activity, horses can be divided into 2 groups: low lactate transport (LT) and high lactate transport (HT) ( Väihkönen and Pösö 1998;Väihkönen et al 1999Väihkönen et al , 2001). The role of MCT and AE1 in lactate transport can be studied by use of inhibitors (Skelton et al 1995;Väihkönen and Pösö 1998;Väihkönen et al 1999Väihkönen et al , 2001) and our previous studies have shown convincingly that interindividual variation is due to variation in MCT activity.…”

“…We have shown previously that, in Standardbred horses, lactate transport activity varies between individuals and, based on this activity, horses can be divided into 2 groups: low lactate transport (LT) and high lactate transport (HT) ( Väihkönen and Pösö 1998;Väihkönen et al 1999Väihkönen et al , 2001). The role of MCT and AE1 in lactate transport can be studied by use of inhibitors (Skelton et al 1995;Väihkönen and Pösö 1998;Väihkönen et al 1999Väihkönen et al , 2001) and our previous studies have shown convincingly that interindividual variation is due to variation in MCT activity. The difference in transport activity is also reflected in vivo; after maximal exercise (trotting race), the lactate concentration in RBC of HT horses is higher than that of LT horses (Väihkönen et al 1999).…”