Relative roles of the sympathetic and parasympathetic systems in the 4-s exercise test.
To evaluate the relative influence of the two branches of the autonomic nervous system on the 4-s exercise test which measures heart rate acceleration at the onset of exercise, 6 healthy male subjects performed the 4-s test under sympathetic blockade with propranolol, parasympathetic blockade with atropine and dual blockade. The magnitude of the 4-s test results (means +/- SD) was significantly different only between the conditions with and without atropine (1.04 +/- 0.03 vs 1.53 +/- 0.33, respectively), with no differences between the control (1.60 +/- 0.25) and the test under sympathetic blockade (1.51 +/- 0.33). These results support the conclusion that the 4-s exercise test is a specific method for the evaluation of parasympathetic activity.
Nobrega
A C
AC
Departamento de Fisiologia, Universidade Federal Fluminense, Niterói, RJ, Brasil.
Castro
C L
CL
Araújo
C G
CG
D000328:Adult; D000704:Analysis of Variance; D001285:Atropine / Q000494:pharmacology*; D001341:Autonomic Nervous System / Q000502:physiology*; D004562:Electrocardiography / Q000187:drug effects; D005080:Exercise Test / Q000187:drug effects; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D011433:Propranolol / Q000494:pharmacology*
D001285:Atropine; D011433:Propranolol