Basal and exercise-induced changes in plasma catecholamines: relationship to age, smoking habits and sampling times.

Contrary to earlier investigations, we have previously shown that the initial increase in venous plasma noradrenaline (NA) during exercise did not differ in young and elderly non-smoking subjects exercising at the same relative workload (75%), and that the greatest increase at maximal workload was observed in the young subjects. In order to determine whether the observed discrepancy could be explained by long-term smoking, plasma NA and adrenaline (A) were evaluated in eight elderly male smokers (mean age 67 years). The results were compared with data reported previously [Jensen et al. (1994) Exercise-induced changes in plasma catecholames and neuropeptide Y: relation to age and sampling times. J Appl Physiol, 76, 1269-1273] in seven young (mean age 27 years) and seven elderly (mean age 61 years) non-smoking male subjects. As shown earlier, basal plasma NA was significantly increased in elderly smokers compared to young and elderly non-smokers. During exercise at 75% of maximal work capacity, no difference was observed between elderly smokers and non-smokers. No difference in plasma A was found between elderly smokers and non-smokers either at rest or during exercise. These findings indicate that the exercise-induced increase in plasma NA did not differ in elderly smokers and non-smokers despite increased resting levels in the former group, and that the increase in the elderly subjects was not augmented compared to that in young subjects.