CUTANEOUS REACTIONS AND SENSATIONS AFTER INTRACUTANEOUS INJECTION OF VASOACTIVE INTESTINAL POLYPEPTIDE AND ACETYLCHOLINE IN ATOPIC ECZEMA PATIENTS AND HEALTHY CONTROLS

We analysed vasoreactions and sensations of atopic eczema (AE) patient s and healthy controls after intracutaneous (i.c.) injection of vasoac tive intestinal polypeptide (VIP) and acetylcholine (ACh), Blood flow was measured by laser Doppler flowmetry (LDF), Plasma extravasation an d flare size were evaluated planimetrically, and sensations were recor ded using visual analog scales. Three groups of subjects (controls, AE patients suffering from acute eczema and AE patients during a symptom -free period) were investigated. We administered VIP separately at con centrations of 1.5 x 10(-7), 1.5 x 10(-6) and 1.5 x 10(-5) M and in co mbination with ACh (5.5 x 10(-6) M) into the volar forearm of the subj ects. Both substances led to an increase in LDF measurements and induc ed a wheal and flare reaction. Blood flow was elevated as a function o f dose after a single VIP application in ail groups. Compared with hea lthy controls, a significant increase in blood flow was measured after combined VIP and ACh administration in AE patients suffering from acu te AE, whereas flare area and plasma extravasation were significantly reduced after single VIP and combined VIP and ACh injections, respecti vely. In all groups, VIP induced dose-dependent pruritus, Compared wit h a control stimulus (0.9% sodium chloride and ACh), combined injectio ns of VIP and ACh had no additional effect on the magnitude of the sen sation. In AE patients, the intensity was similar to that experienced by the control subjects, but the quality of sensation was different: A Ch induced, pain in the control subjects, pruritus in AE patients, and a mixture of pain and itching in AE patients showing no symptoms. Our results suggest that VIP- and ACh-induced skin reactions and the qual ity of the sensations depend on the activity of the atopic eczema. Con firming our former studies, AE patients develop a different quality of sensation after ACh administration and also after administration of V IP combined with ACh. Therefore, we suggest that ACh might be involved in the pathomechanisms of pruritus in AE.