 Experimental Design. All subjects were healthy as confirmed by medical history and physical examinations, blood profile, echocardiographic evaluation and were not taking medications. All subjects abstained from caffeine for 24 hours before the study. All studies were performed in the post-absorptive state with exception of blood sample collection. Microneurography was performed in a quiet, temperature-controlled room on morning at approximately the same time of day. The right leg was positioned for microneurography. After an adequate nerve recording site was obtained, the subject rested quietly for 10 minutes. Baseline muscle sympathetic nerve activity, blood pressure, and heart rate were then recorded continuously for 4 minutes. Acute Color Word Stroop Test was then performed for 3 minutes. After 10 minutes of recovery all patients completed 30 hand grip isometric contraction followed by 2 minutes of brachial occlusion. 