The effect of acute exercise on GLUT4 levels in peripheral blood mononuclear cells of sled dogs

Abstract

Using sled dogs as exercise model, our objectives of this study were to (1) assess the effects of one acute bout of high-intensity exercise on surface GLUT4 concentrations on easily accessible peripheral blood mononuclear cells (PBMC) and (2) compare our findings with published research on exercise induced GLUT4 in skeletal muscle. During the exercise bout, dogs ran 5 miles at approximately 90% of VO2 max. PMBC were collected before exercise (baseline), immediately after exercise and after 24 h recovery.GLUT4 was measured via ELISA. Acute exercise resulted in a significant increase on surface GLUT4 content on PBMC. GLUT4 was increased significantly immediately after exercise (~50%; p<0.05) and reduced slightly by 24 h post-exercise as compared to baseline (~22%; p>0.05). An effect of acute exercise on GLUT4 levels translocated to the cell membrane was observed, with GLUT4 levels not yet returned to baseline after 24 h post-exercise. In conclusion, the present investigation demonstrated that acute high-intensity exercise increased GLUT4 content at the surface of PBMC of sled dogs as it has been reported in skeletal muscle in other species. Our findings underline the potential use of peripheral blood mononuclear cell GLUT4 protein content as minimally invasive proxy to investigate relationships between insulin sensitivity, insulin resistance, GLUT4 expression and glucose metabolism.

Exercise Increases Glucose Transporter-4 Levels on Peripheral Blood Mononuclear Cells

“…Similar to Maratou et al (19), we also reported an inverse relationship with PBMC GLUT4 and HOMA-IR. In a follow up study we reported a 50% increase in PBMC GLUT4 with a single bout of exercise in sled dogs (22), akin to what is reported in skeletal muscle of humans and rodents (7, 16, 23, 24). In this study we extend these finding in humans for the first time, which further supports the hypothesis that conditioning increases GLUT4 concentration in PBMC.…”

“…If the cells remain intact, then the GLUT4 measured represents surface GLUT4. In developing this method, we validated surface GLUT4 via two different methods; 1) we found the same significant increase in PBMC GLUT4 after exercise when analyzed by flow cytometry as we did with this technique (unpublished) and 2) rupturing the cells with sonication resulted in a 3-fold higher increase in GLUT4 concentration (21, 22, 27). Using BD separation tubes results in a diffuse layer of mononuclear cells that can be carefully collected and gently washed.…”

“…Statistical analysis was completed on both ng GLUT4/g of protein concentrations and GLUT4 concentrations without adjusting for protein content. Both resulted in significant differences, therefore we chose to report on GLUT4 concentrations without adjustment for protein (Figure 2)(21, 22).…”

Hyperinsulinemia: A unifying theory of chronic disease?

“…However, GLUT4 have a relatively short halflife. 19 5. If hyperglycemia persists, the pancreas maintains insulin secretion.…”

Hyperinsulinemia: Best management practice

“…GLUT4 adaptation can occur with single bouts of exercise and effects persist for up to 40 hours. 20,21 This suggests that, especially in the early days of adopting physical activity, varying the activities undertaken may maximize GLUT4 adaptation while minimizing effects from over-secretion of cortisol or glucagon. While the literature suggests the ideal activity should comprise a combination of resistance training and HITT protocols, the final selection of physical activities may be influenced by personal circumstances, including preference, health status and levels of training required.…”