Does plasma L-arginine level play a role in regulation of blood pressure during exercise and autonomic nervous...

Little is known of L-arginine's role in autonomic nervous regulation and physiological responses to dynamic exercise. We assessed heart rate and blood pressure during a maximal bicycle ergometer test and heart rate variability at rest in 15 healthy male volunteers, age 22-38 years. Venous blood samples for plasma L-arginine measurements were taken when subjects were sitting at rest before and at the end of exercise. The autonomic nervous function was assessed with time and frequency domain analysis of heart rate variability. Plasma L-arginine level decreased during maximal exercise from 71.4 mumol l-1 to 51.0 mumol l-1 (P < 0.0001) for all subjects studied. The systolic blood pressure during the maximal exercise test was inversely correlated with plasma L-arginine level at rest (r = -0.70, P < 0.01). Normalized low frequency band of power spectral analysis of heart rate variability correlated with L-arginine level at rest (r = 0.66, P < 0.01). In conclusion, plasma L-arginine level decreased in physical exercise, and plasma L-arginine level at rest was positively associated with the sympathetic component of power spectral analysis of heart rate variability at rest, and inversely with systolic blood pressure during physical exercise.