Is autonomic support of arterial blood pressure related to habitual exercise status in healthy men?
We determined if the tonic autonomic nervous system (ANS) contribution to arterial blood pressure (BP) maintenance in humans is related to habitual endurance exercise status. Twenty-three healthy young (age 18-31 years) males, 11 endurance exercise-trained and 12 untrained, were studied. Maximal oxygen consumption was higher (P < 0.001) and resting heart rate and body fatness were lower (P < 0.05) in the exercise-trained men. Plasma noradrenaline concentrations and BP decreased from baseline levels in response to ganglionic blockade (intravenous trimethaphan) in both groups (all P < 0.001). The absolute (Delta mmHg: systolic = -35 +/- 2 vs. -32 +/- 4; diastolic = -13 +/- 2 vs. -10 +/- 2; mean = -21 +/- 2 vs. -17 +/- 3) and relative (Delta%: systolic = -35 +/- 2 vs. -31 +/- 3; diastolic = -26 +/- 3 vs. -20 +/- 3; mean = -31 +/- 2 vs. -26 +/- 3) decreases in BP were not significantly different between the endurance-trained and untrained men. There were no significant group differences in the heart rate, stroke volume, cardiac output or systemic vascular resistance (conductance) responses to trimethaphan. Systemic vascular alpha-adrenergic sensitivity (slope of the increase in mean BP with incremental phenylephrine infusion during ganglionic blockade) also did not differ in the two groups (endurance-trained: 3.2 +/- 0.5; untrained: 3.2 +/- 0.7 mmHg (ng phenylephrine)(-1) (ml plasma)(-1)). In the pooled sample, the decrease in mean BP during trimethaphan was related to baseline and changes in plasma noradrenaline concentrations (r = 0.58-0.65, P < 0.001) and alpha-adrenergic sensitivity (r = 0.49, P < 0.02). Our results suggest that the endurance exercise-trained state is not obviously associated with altered ANS support of BP in healthy young men. Basal sympathetic nervous system (SNS) activity and alpha-adrenergic vascular sensitivity are significant physiological correlates of ANS support of BP in this population.
Jones
Pamela Parker
PP
Department of Kinesiology and Applied Physiology, University of Colorado at Boulder, Boulder, CO 80309, USA. pamela@spot.colorado.edu
Shapiro
Linda F
LF
Keisling
Gretchen A
GA
Quaife
Robert A
RA
Seals
Douglas R
DR
D000293:Adolescent; D000328:Adult; D001341:Autonomic Nervous System / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D005070:Evans Blue; D015444:Exercise / Q000502:physiology*; D005730:Ganglionic Blockers / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006728:Hormones / Q000097:blood; D006801:Humans; D010101:Oxygen Consumption / Q000502:physiology; D010953:Plasma Volume; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology
D005730:Ganglionic Blockers; D006728:Hormones; D011942:Receptors, Adrenergic, alpha; D005070:Evans Blue