Use of skin conductance changes during mental stress testing as an index of autonomic arousal in cardiovascular research.

Mental stress testing is used to study the cardiovascular changes caused by psychologic stress. To examine the effects of cardiac drugs on mental stress-induced changes, it is useful to attain a degree of arousal that can be replicated in serial studies. Skin conductance level, a cholinergically mediated index of arousal, was assessed for its stability in serial studies and under conditions of beta-blockade. In normal subjects, skin conductance increased in response to mental stress (p < 0.001) and was stable across three sessions. In patients with mild hypertension, skin conductance was elevated during mental stress during both placebo and nadolol therapy (p < 0.001). As expected, nadolol reduced baseline and stress-induced peak arterial pressure and heart rate but had no significant effect on skin conductance. Thus skin conductance level can serve as a stable and useful index of autonomic arousal in clinical trials, even in patients using beta-blocking medications.