Fealey, Robert D.

The complex forearm vasodilator response during mental stress (MS) is mediated in part by unchanged or decreased forearm muscle sympathetic nerve activity. However, immediately after MS, nerve activity is increased. To determine the effect of chronic sympathetic denervation on forearm blood flow (FBF, [ml/100ml forearm volume/min]) response to MS, we studied patients pre and post sympathotomy (ETS) for palmar hyperhidrosis. 15 healthy subjects (11 F; 19‐32 yr) with a mean BMI of 23 ± 5 kg/m2 were studied 1 day‐6 mo before ETS and 1‐6 mo after ETS. FBF (plethysmography) was recorded during baseline, 3 min Stroop test, and 2 min post‐MS recovery. ETS did not affect resting HR, BP or FBF. However, resting forearm vascular resistance (FVR, [MAP/FBF]) was reduced after ETS (50 ± 20 vs 33 ± 14, p < 0.01) and forearm vascular conductance (FVC, [(FBF/MAP)*100]) was increased (3 ± 2 vs 4 ± 2, p < 0.05). MS caused significant increases in FBF and FVC, and a decrease in FVR, and these responses were unaffected by ETS. However during post‐MS recovery, ETS caused a significant increase in FBF (2 ± 1 vs 3 ± 1), FVC (3 ± 1 vs 4 ± 2), and a decrease in FVR (52 ± 22 vs 32 ± 16) (p < 0.01). Chronic sympathetic denervation influences post‐MS forearm vasoconstriction, which likely has minor hemodynamic consequences but confirms a greater role for sympathetic control of FBF in the post‐MS period as opposed to during MS. NIH HL‐089331, NS‐32352