Alkalosis and the plasma catecholamine response to high-intensity exercise in man.

Purpose: The aims of this study were to examine the plasma dopamine response to a controlled bout of short-duration high-intensity exercise and investigate the magnitude of the plasma dopamine (DA), norepinephrine (NE), and epinephrine (EPI) responses to this exercise after induced alkalosis.

Methods: Eight male subjects were given in randomized order either; PLAC 0.3 g.kg(-1) body mass CaCO3 + 1 g NaCl, 0.3CIT 0.3 g.kg(-1) or 0.5CIT 0.5 g.kg(-1) body mass tri-sodium citrate in 500 mL water. One hour after ingestion subjects performed a 2-min cycle test at a workload calculated to elicit 110% VO(2max). Plasma catecholamines were measured using high performance liquid chromatography with electrochemical detection.

Results: Antecubital venous blood pH and blood base excess (BBE) were significantly increased after ingestion of sodium citrate compared with placebo (P < 0.05). All postexercise sodium citrate blood pH and BBE values were significantly greater than placebo (P < 0.05). High-intensity exercise did not affect resting plasma DA concentrations. Peak plasma NE and EPI concentrations occurred immediately postexercise [NE PLAC 4.6 +/- 2.1 ES = 1.2, 0.3CIT 4.2 +/- 1.8 ES = 1.5, 0.5CIT 4.6 +/- 2.2 nmol.L(-1) ES = 1.2; EPI PLAC 0.6 +/- 0.3 ES = 1.3, 0.3CIT 0.5 +/- 0.2 ES = 1.3, 0.5CIT 0.5 +/- 0.3 nmol.L(-1) ES = 0.8] and were still elevated 5 min postexercise (P < 0.05). The magnitude of the plasma dopamine, norepinephrine and epinephrine response to exercise was unaltered with either 0.3CIT or 0.5CIT.

Conclusion: This study has demonstrated that performance of a controlled bout of high-intensity exercise did not alter the plasma dopamine concentration. In addition, alterations in blood alkalosis did not influence the magnitude of the plasma dopamine, norepinephrine or epinephrine responses to exercise.