Acute catecholaminergic responses to mental and physical stressors in man

The measurement of plasma norepinephrine (NE) and epinephrine (EPI) levels has provided a means to assess sympathetic and adrenal medullary responses to stressors. To address the issue of specificity of these responses to mental or physical stress, we measured plasma norepinephrine (NE) and epinephrine (EPI) levels in male volunteers who underwent either exhaustive graded treadmill exercise or a 30 min stressful interview. We found that graded treadmill exercise to exhaustion (mean duration of exercise 15.2 ± 0.7 min) was associated with similar increases in both NE (239 per cent) and EPI (201 per cent) immediately after completing exercise. Elevated values rapidly returned to baseline levels after exercise. In response to the 30min stressful interview where subjects remained seated throughout the stressor, there were smaller but highly significant increases in plasma levels of both NE (67 per cent) and EPI (82 per cent) within the first 10min of the interview. By the last 10min of the interview, EPI levels were already returning to baseline values while NE levels remained elevated throughout and for at least 5min after the exam. These findings demonstrate that a stressful interview is associated with increases in both NE and EPI levels which are qualitatively similar to the responses to a physical stressor.