Considerations on pulsoplethysmographic changes in fingers due to iontophoresis with methacholine in subjects with Raynaud's phenomenon

This paper presents a study of plethysmographic changes induced by methacholine (a derivative of acetylcholine) administered via iontophoresis in a population of 41 young women with apparently primary Raynaud's disease. All patients presented with a very clear statistically significant sphygmic increment, obviously connected with the vasodilatation caused by methacholine. Moreover, in nearly half of the 23 cases whose reaction to passive postural variations was successively examined by plethysmography, the district circulatory response was characterised by persistent neurogenous vasoconstriction due to methacholine or by inadequate vasomotor EDRF mediated modulation. The authors believe that their findings serve as further evidence of the pathogenetic mechanisms of Raynaud's disease. This is because they highlight the role played by "balance of vessel motility" which would guarantee district circulatory homeostasis. Concrete proof thus corroborates well known indirect evidence that a pathological vasospasm can be triggered and persist when two fundamental conditions are met: a) intense vasoconstriction initially of neurological origin and successively reinforced by biohumoural synergic stimuli; b) the breakdown of the capacity for EDRF mediated intrinsic vasomotor modulation. It is suggested that the prevalence of one or the other factor would lead to a variety of clinical pictures denoting vascular acrosyndromes of this type. The ability to single out such clinical pictures by adding the iontophoresis test with methacholine to routine screening procedures for the presence of Raynaud's disease, would allow physicians to make more accurate diagnosis and improve therapy.