Renalase is a FAD-dependent amine oxidase, secreted by the kidney into blood and shown to have significant cardiovascular actions, attributed to its catecholamine-metabolising activity. Renalase activity has not been yet investigated in physiological and stress conditions in humans. Therefore, this study aims to investigate the impact of acute exercise on renalase activity.

A healthy volunteer (aged 25 yrs) performed an incremental exercise bout on cycle ergometer, until exhaustion. Salivary and blood samples were collected at rest (baseline), at 3-min intervals along the trial, 1 min after reaching exhaustion and 15, 30 and 60 min of the recovery. Circulating catecholamines, assayed by salivary alpha-amylase (sAA) detection, plasma renalase, antioxidant (PAC) and oxidant (POC) capacities were determined. Data obtained at different time points were expressed as % changes in concentration vs. baseline values.

During exercise bout, sAA and renalase increased by 21.2 and 30.9%, respectively. PAC decreased up to 4%; while, POC increased up to about 20%. The sAA reached its peack after 15 minutes, corresponding to the maximum renalase decrease. Interestingly, PAC strongly increased with a time course almost overlapping that of sAA. These data suggest that PAC and catecholamine trends were somehow related each other. Conversely, the POC trend was similar to that of renalase, suggesting that renalase may influence POC.

Taken together, these results, even though restricted to a single subject, provide the first experimental evidence about the stress-induced renalase response, possibly influencing the oxidative-antioxidant coupling, related to catecholamines changes.