title: Biphasic vasomotor reflex responses of the hand skin following intradermal injection of melittin into the forearm skin.
abstract: Melittin is the main toxin of honeybee venom. Previously, we have reported that intradermal injection of melittin into the volar aspect of forearm in humans produces a temporary pain and a subsequent sustained increase in the skin temperature due to axon reflex. To clarify the interaction between nociceptive inputs and vascular changes, we studied the influence of noxious stimulation by intradermal melittin on the vasomotor control of the distal extremities in human volunteers. Temperature changes of the bilateral palmar surface were recorded by means of a computer-assisted infrared thermography. Unexpectedly, we found a biphasic response of skin temperature. The skin temperature of both fingers and hands decreased immediately after the melittin injection and then increased well above the control level, prior to the injection. There was a considerable individual variation in the baseline skin temperature, prior to melittin. The skin temperature in a finger/hand with lower preinjection value increased more markedly in the second phase. Consequently, the individual variation in the peak temperature of the second phase was less pronounced. The initial decrease was interpreted as sympathetic vasoconstrictor reflex induced by noxious stimulation and the later increase as release of sympathetic vasomotor tone.
authors.affiliation: Department of Physiology, Shiga University of Medical Science, Seta, Otsu 520-2192, Japan. koyama@belle.shiga-med.ac.jp
authors.forename: Natsu
authors.initials: N
authors.lastname: Koyama
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Hirata
authors.forename: Koichiro
authors.initials: K
authors.lastname: Hori
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Dan
authors.forename: Toshikatsu
authors.initials: T
authors.lastname: Yokota
mesh_terms: D000328:Adult; D001808:Blood Vessels / Q000187:drug effects* / Q000294:innervation; D005260:Female; D007839:Functional Laterality / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D008555:Melitten / Q000494:pharmacology*; D036421:Nerve Fibers, Unmyelinated / Q000187:drug effects / Q000502:physiology; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology; D010146:Pain / Q000139:chemically induced / Q000503:physiopathology; D010147:Pain Measurement / Q000187:drug effects; D012018:Reflex / Q000187:drug effects* / Q000502:physiology; D012867:Skin / Q000187:drug effects* / Q000294:innervation; D012881:Skin Temperature / Q000187:drug effects / Q000502:physiology; D017779:Sympathetic Fibers, Postganglionic / Q000187:drug effects* / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects* / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology; D014666:Vasomotor System / Q000187:drug effects* / Q000502:physiology
chemical_list: D008555:Melitten