16 METABOLIC RESPONSE TO MODERATE EXERCISE IN LAMBS WITH AN AORTOPULMONARY SHUNT

Abstract

The normal metabolic response to moderate exercise consists of a slight increase in glucose (glue) and a considerable increase in free fatty acids (FFA) in blood. In earlier studies we have demonstrated that at rest, after an overnight fast, lambs with an aortopulmonary shunt (SH) had lower concentrations of glue and FFA than control (C) lambs. We wondered, whether SH lambs with low glue and FFA were able to increase their arterial concentrations during exercise just like C lambs. Therefore, we studied 6 7-week-old SH lambs and 6 C lambs of the same age after an overnight fast at rest and during moderate exercise (tredmill; 50 % of Vo2-max; 30 rain). At rest as well as during exercise, 3 blood samples were taken at intervals of 10 min. At rest, mean arterial concentrations (mmol/l) of glue (SH: 3.37 ± 0.21 vs. C; 4.48 ± 0.53, mean ± SD, p < 0.05) and FFA (SH: 0.57 ± 0.17 vs. C: 0.80 ± 0.20, p < 0.05) were lower in SH than in C lambs. During exercise, glue (SH: 3.59 ± 0.19 vs. C: 5.15 ± 0.80, p < 0.05) and FFA (SH: 0.79 ± 0.32 vs. C: 1.23 ± 0.43, p < 0.05) increased significantly in SH and C lambs (p < 0.05). However, the relative increment of glue during exercise was lower in SH than in C lambs (7 ± 5 % vs. 15 ± 7 %, p < 0.05). The relative increment of FFA was not different (SH: 38 ± 37 % vs. C: 56 ± 47 %, p = 0.48). We conclude that, despite lower gluc and FFA at rest, SH lambs demonstrate a metabolic response of increment of gluc and FFA during moderate exercise like C lambs, However, the relative increment for gluc was lower in SH lambs. We speculate that this is due to an earlier glycogen depleted state in SH lambs.