Impact‐induced muscle damage and urinary pterins in professional rugby: 7,8‐dihydroneopterin oxidation by myoglobin

Abstract

Muscle damage caused through impacts in rugby union is known to increase oxidative stress and inflammation. Pterins have been used clinically as markers of oxidative stress, inflammation, and neurotransmitter synthesis. This study investigates the release of myoglobin from muscle tissue due to force-related impacts and how it is related to the subsequent oxidation of 7,8-dihydroneopterin to specific pterins. Effects of iron and myoglobin on 7,8-dihydroneopterin oxidation were examined in vitro via strong cation-exchange high-performance liquid chromatography (SCX-HPLC) analysis of neopterin, xanthopterin, and 7,8-dihydroxanthopterin. Urine samples were collected from 25 professional rugby players pre and post four games and analyzed for myoglobin by enzyme-linked immunosorbent assay, and 7,8-dihydroneopterin oxidation products by HPLC. Iron and myoglobin oxidized 7,8-dihydroneopterin to neopterin, xanthopterin, and 7,8-dihydroxanthopterin at concentrations at or above 10 μM and 50 μg/mL, respectively. All four games showed significant increases in myoglobin, neopterin, total neopterin, biopterin, and total biopterin, which correlated between each variable (P < 0.05). Myoglobin and iron facilitate 7,8-dihydroneopterin oxidation to neopterin and xanthopterin. In vivo delocalization of myoglobin due to muscle damage may contribute to oxidative stress and inflammation after rugby. Increased concentrations of biopterin and total biopterin may indicate production of nitric oxide and monoamine neurotransmitters in response to the physical stress.

Urinary myoglobin quantification by high-performance liquid chromatography: An alternative measurement for exercise-induced muscle damage

“…The concentrations observed following each of the mixed martial arts events suggest that a training session is of greater intensity than a simulated contest, most likely a result of the difference in duration. Moreover, it is comparable to other 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 high-impact sports that have shown similar changes in urinary myoglobin [4,5], which demonstrate the severity of the sport that has been widely neglected in exercise research. Detection of myoglobin at an absorbance of 400 nm produced a clear visible peak with no observed tailing or interference from neighboring urinary analytes allowing for clear interpretation, whereas the dilution in 10 mM ammonium acetate (pH 7.0) seemed to alleviate any stabilization concerns that had been previously noted over a 24-h period [14].…”

“…Feinfeld and coworkers [9] observed patients with acute rhabdomyolysis exceeding concentrations of 1 mg/ml, whereas previous studies have suggested that patients with values exceeding 20 mg/ml are at more of an increased risk of decreased renal function [21,27]. In addition, values as high as 32.9, 410, and 3000 mg/ml have been observed following crush trauma [3], strenuous military training [13], and myocardial infarction [2], respectively, whereas values reaching 52 and >100 mg/ml have been observed in competitors following a marathon [28] and professional rugby [5], respectively. Therefore, in an exercise and/or serious trauma scenario where muscle damage is expected to rise significantly, this assay may provide the most cost-effective and operator-friendly option for simple and rapid quantitation for both small and large cohorts suffering mild to severe skeletal muscle stress in a range that is widely accepted as "clinically relevant.…”

“…Myoglobin, the hemoprotein that facilitates oxygen storage for sustained oxidative phosphorylation in muscle fibers, is a key marker of muscle damage that has notably been employed to assess the severity of injury and monitor the recovery of individuals suffering from rhabdomyolysis [1], myocardial infarction [2], accidental trauma [3], and exercise [4,5]. Muscle damage quantification is also pertinent to the diagnosis of exercise-induced physiological stress for the management of athlete recovery and performance.…”

Realising the Potential of Urine and Saliva as Diagnostic Tools in Sport and Exercise Medicine

“…The advantage of chromatography is the simultaneous determination of creatinine with the analyte that requires creatinine correction. Usually analysed at 234 nm by ultra-violet detection, the method has been used effectively in the quantification correction of neopterin [26,240,241], desmosine [242], catecholamines, and metanephrines [243].…”

“…The extremely rapid elimination kinetics of myoglobin [278] in comparison to more commonly utilised plasma markers such as creatine kinase [279,280] make it an ideal biomarker that provides an immediate evaluation of severity. It has been used extensively in several forms of exercise [20,240,241,[281][282][283][284][285] and is quantifiable using both ELISA [241] and reverse-phase high performance liquid chromatography (RP-HPLC) [284].…”