RESUMEN
OBJECTIVE: To study the effect of exercise on hemodynamic profiles and red blood cell (RBC) concentrations of adenosine-5'-triphosphate (ATP). METHODS: Male Sprague-Dawley (SD) rats (n = 9) were exercised on a treadmill for 15 min at a speed of 10 m/min with a 5% gradient after an hour settling down in a restrainer. Blood samples were collected via an indwelling carotid artery catheter using a 'Stopping Solution' from each rat before, during and after exercise. Hemodynamic recordings were collected continuously throughout the experiment. Concentrations of ATP and other purine nucleotides in the RBCs were determined by a validated high-performance liquid chromatography (HPLC) assay. A control group (n = 12) was treated the same way except without the exercise. Data between groups were analyzed by analysis of variance (ANOVA) and Student's t-test, and differences were considered significant when p < 0.05. RESULTS: Exercise increased systolic blood pressure (SBP; 141±23 vs. 132±17 mmHg) and heart rate (HR; 420±33 vs. 397±41 bpm), but decreased diastolic blood pressure (DBP; 105±18 vs. 110±14 mmHg). This was followed by a postexercise condition when SBP, DBP, and HR were decreased for the remainder of the experiment. RBC concentrations of ATP and guanosine-5'-triphosphate (GTP) increased significantly during exercise and continued to increase for 5 hours postexercise (1.5±0.75 vs. 0.96 vs. 0.36 mM for ATP; and 0.14±0.061 vs. 0.058±0.030 mM) (p < 0.05). CONCLUSION: Exercise increased RBC ATP concentrations in a rodent model, which was correlated with the decrease in BP and HR postexercise.