Search

Background: Iron is a vital trace element for energy production and oxygen transportation; importantly, it is essential to athletic performance. Maintaining iron balance is tightly controlled at systemic and cellular levels. This study aimed to determine serum iron tests, hepcidin levels, and cellular iron import and export activities in peripheral blood mononuclear cells (PBMCs) in ultramarathon runners to elucidate the association of systemic inflammation response and iron metabolism. Methods: Sixteen amateur runners were enrolled. Blood samples were taken 1 week before, immediately, and 24 h after the run. Plasma hepcidin levels were measured by enzyme-linked immunosorbent assay. The expression levels of divalent metal iron transporter 1 (DMT1), ZRT/IRT-like protein 14 (ZIP14), transferrin receptor 1 (TfR1), and ferroportin (FPN) in PBMCs were measured using real-time quantitative reverse transcription-polymerase chain reaction. Results: Serum iron concentrations and transferrin saturation significantly decreased immediately after the race and dramatically recovered 24 h post-race. Serum ferritin levels had a statistically significant rise immediately after the race and remained high 24 h after the completion of the race. Ultramarathons were associated with increased plasma interleukin-6 concentrations corresponding to the state of severe systemic inflammation and therefore boosted plasma hepcidin levels. The expression levels of DMT1 and FPN mRNA were markedly decreased immediately and 24 h after the race. The ZIP14 and TfR1 mRNA expression in PBMCs significantly decreased immediately after the race and returned to the baseline level at 24 h post-race. Positive significant correlations were observed between plasma hepcidin and ferritin levels. Conclusion: Iron homeostasis and systemic inflammatory response are closely interconnected. Cellular iron import and export mRNA activities in PBMCs were acutely inhibited during an ultramarathon. [ABSTRACT FROM AUTHOR]

Background: The change in N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels follows a paradox imposed by strenuous endurance exercise. Previous reports showed significant body weight (BW) loss was common in ultramarathon runners. This study investigated whether the BW change and renin--angiotensin--aldosterone system activation contribute to exercise-induced NT-proBNP release. Methods: A total of 26 participants who finished a 100 km ultramarathon in Taiwan were enrolled. For each participant, blood samples and spot urine samples were collected 1 week before the race, as well as immediately and 24 hours after the finish. BW change was recorded to monitor the hydration status. Results: Prolonged endurance exercise led to a substantial increase in NT-proBNP. Compared with prerace values, NT-proBNP levels significantly increased immediately after the race (24.3 ± 20.2 pg/mL to 402.9 ± 305.9 pg/mL, p < 0.05) and maintained high levels until 24 hours after the race (143.7 ± 126.1 pg/mL, p < 0.05). The fractional excretion of sodium values was below 1% in three different time points. The 100 km ultramarathon resulted in significant BW loss and elevated renin and aldosterone levels. However, only 24 hours after the race, a positive significant relationship was found between NT-proBNP and aldosterone levels (p = 0.007, r² = 0.267), but a negative significant relationship between NT-proBNP and BW increased during the recovery phase (p < 0.001, r² = 0.372). Conclusion: The mechanism of NT-proBNP release immediately following the race was multifaceted. During the recovery phase, rehydration might lead to the decrease of NT-proBNP. Our observations with regard to aldosterone and NT-proBNP might be in response to help the body maintains hydration state. [ABSTRACT FROM AUTHOR]