Exercise-induced Hemolysis And Iron Regulation In Response To Mechanical Stress

Abstract

Hepcidin, a liver derived hormone, plays a role in iron regulation due to decreases in iron absorption and/or iron recycling. Exercise-induced hepcidin secretion is thought to be augmented by increased interleukin-6 (IL-6) and hemolysis (i.e., disruption of red blood cells). However, it is difficult to comprehend the contributions of hemolysis during exercise for hepcidin secretion. PURPOSE: To investigate the impact of exercise-induced hemolysis by a drop jump with concomitant repetitions of mechanical stress on hepcidin response. METHODS: Ten healthy males attended in this study [means ± SD, age: 24 ± 3 yrs, height: 170.6 ± 5.8 cm, body weight: 64.4 ± 7.2 kg]. Participants conducted two trials on different days, consisting of drop jump exercise to induce mechanical stress (DJ trial) or without exercise (CON trial). DJ trial consists of 100 bouts of drop jump from a 60 cm box, and each jump was conducted with their maximal effort. Blood samples were collected before trials, immediately, 1 h, 2 h and 3 h after completion of trials. The timing of blood sampling in CON trial was matched with DJ trial. A p value less than 0.05 was considered statistically significant. RESULTS: Baseline serum ferritin concentration did not significantly differ between DJ (73.1 ± 42.8 ng/mL) and CON trials (65.2 ± 31.6 ng/mL, p = 0.135). Serum iron and myoglobin concentration significantly increased and serum haptoglobin concentrations significantly decreased post-exercise in DJ trial (p < 0.05). Plasma IL-6 concentration did not increase in either trial (p > 0.05). Serum hepcidin concentration significantly increased 3 h after both trials (p < 0.05); however, the relative increase in serum hepcidin concentrations did not differ significantly between DJ and CON trials (77.4 ± 70.6% vs. 39.1 ± 51.5%, p = 0.184). CONCLUSIONS: Hemolysis was occurred following the drop jump exercise, while post-exercise IL-6 and hepcidin elevations were not different between the trials. Mechanical stress-induced hemolysis may not be sufficient to induce hepcidin elevation without IL-6 changes.