Vascular and humoral sympathetic nervous system reactivity during mental arithmetic in primary Raynaud's phenomenon

To investigate the hypothesis of a sympathetic imbalance in the pathophysiology of digital vasospasms during stress we measured vascular and sympathetic nervous system reactivity during a standardized mental arithmetic test in 12 patients with primary Raynaud's phenomenon in comparison to 12 healthy control subjects. Blood pressure, heart rate, forearm blood flow and fingertip laser Doppler flux were measured together with the venous concentrations of norepinephrine and epinephrine from the back of the hand before and during mental arithmetic in a climate room. No significant differences in circulatory or sympathetic reactivity were found between both groups except for fingertip skin circulation with a small decrease of laser Doppler flux (-11.6%) in controls, whereas it increased in PRP (46.6%; p less than 0.05 between both groups). Baseline skin blood flow was inversely correlated with changes in laser Doppler flux (R = -0.91; p less than 0.001; no. 24) irrespective of the diagnosis when baseline skin bloodflow is low a vasodilatory response occurs and when it is high a vasoconstrictive response is seen. Initial laser Doppler flux was lower while baseline diastolic blood pressure, heart rate and (nor)epinephrine concentrations were significantly higher in Raynaud-patients suggesting an increased sympathetic activity at rest in primary Raynaud's phenomenon.