Generation and transit pathway of H+ is critical for inhibition of palmar sweating by iontophoresis in water

Abstract

Passing galvanic current across the skin (known as "tap water iontophoresis" or TWI) inhibits sweating; however, its mechanism of action is unclear. Using improved methods, we confirmed that anodal current has more of an inhibitory effect than cathodal current, water is superior to saline, and the inhibitory effect is a function of the amperage used. To address the importance of current flowing through the pores, a layer of silicone grease was placed on the skin to reduce the shunt pathway across the epidermis. With silicone, total skin conductance decreased 60% without the sweat pores being occluded, swelling of the stratum corneum and collapse of the poral lumen was prevented, and current-induced inhibition of sweating was enhanced, most likely because of an increase in current density in the pores. The pH of anodal water, but not of saline, dropped to 3, whereas that of cathodal water increased to 10 during passage of current through the skin. Acidified anodal water was superior to alkaline water. Sweat glands isolated from TWI-induced anhidrotic palmar skin responded to methacholine in vitro, but the sweat rate and pharmacological sensitivity were slightly lowered. Thus the strong acidity generated by hydrolysis of water in the anodal bath and the further accumulation of H+ in the sweat duct by anodal current may be responsible for TWI-induced inhibition of sweating due to an unknown lesion(s) in the duct or sweat pore. The secretory coil function may also be altered because of exposure to intense acidity during TWI. The importance of H+ movement into the sweat pore for inhibition of sweating could be further exploited to develop new strategies for the control of sweating.

Current-Induced Vasodilation during Water Iontophoresis (5 min, 0.10 mA) Is Delayed from Current Onset and Involves Aspirin Sensitive Mechanisms

“…Thus, a progressive resistance decrease of the skin during current application may be required before local direct suprathreshold current densities allow for direct activation of nociceptors. As concerns an indirect activation of nociceptors, it has been shown that slow progressive local skin [38]or bath solution [24]pH changes result from current application in iontophoresis and that low pH is known to powerfully activate nociceptors [39]. The delay required to reach a sufficient pH change to activate nociceptors could appear as the simplest explanation for the delay in the abrupt vasodilation (∼90 s) observed at the cathode.…”

“…22]] following nociceptor activation is involved in the current-induced vasodilation attending iontophoresis [6, 23], either by a direct or indirect activation of nociceptors. Among the possible indirect mechanisms of nociceptor activation is a progressive local pH change, which would result from current application [24]and which could stimulate the nociceptors. Two consequences of this hypothesis arise.…”

Focal hyperhidrosis: diagnosis and management

“…The mode of action is not yet clear, but it is postulated that a charged particle obstructs the duct or the electrical change disrupts eccrine gland secretion. 30 The procedure entails placing the hands or feet in a shallow basin filled with water, through which an electric current is passed. Iontophoresis is primarily used for focal palmoplantar hyperhidrosis, since the hands and feet are the easiest body parts to submerge in water.…”

Hyperhidrosis and Its Treatment: A Safe and Effective Alternative in the Treatment of Palmoplantar Hyperhidrosis, Iontophoresis

“…içinde yavaş yavaş azaltılarak seans sonlandırılır (34). Yapılan çalışmalarda anot uçla tedavi edilen taraftaki inhibitör etkinin daha fazla olduğu bulunmuştur (34,45,53). Bazı araştırmacılar her seansın ortasında anot ve katot uçların yerlerinin değiştirilmesini önermişlerdir (9,39).…”