title: Inhibitors of nitric oxide synthase in human skin.
abstract: The aim of this study was to investigate in human skin in vivo the role of nitric oxide in maintaining resting vascular tone, in the vasodilatation caused by local warming and by ultraviolet B light exposure, and in the response to exogenous calcitonin gene-related peptide (CGRP). Cutaneous blood flow was assessed by planimetry of the visible erythema or pallor and by laser Doppler flowmetry. Intradermal injection of the inhibitor of nitric oxide synthase, NG-nitro-L-arginine methyl ester (L-NAME; 25 nmol), into forearm skin produced a visible pallor and a reduction of blood flow at a controlled ambient temperature of 21 degrees C. The control, NG-nitro-D-arginine methyl ester (D-NAME; 25 nmol) or NG-monomethyl-L-arginine (L-NMMA; 25 nmol) did not cause pallor or reduce blood flow. L-NAME and L-NMMA caused dose- and time-dependent increases in pallor, and reductions in cutaneous blood flow in skin that had been locally warmed by immersion in water at 45 degrees C and in skin that had been exposed to ultraviolet B light. D-NAME and D-NMMA at comparable concentrations did not have the effects on skin blood flow observed with the L forms. L-NAME and L-NMMA both inhibited the increased blood flow in human skin caused by the intradermal injection of CGRP (12.5 or 25 pmol). The reduction of CGRP-induced increase of blood flow by L-NAME was reversed by L-arginine. Neither D-NAME nor D-NMMA inhibited the increase in blood flow caused by CGRP. Neither L-NAME nor L-NMMA inhibited the increase in blood flow in human skin caused by the intradermal injection of prostaglandin E2 (63 pmol). The data show that nitric oxide is involved in the maintenance of resting blood flow in human skin and also in the cutaneous vasodilator responses to local warming, ultraviolet B irradiation, or injection of CGRP.
authors.affiliation: Department of Dermatology, University College London Medical School, U.K.
authors.forename: P C
authors.initials: PC
authors.lastname: Goldsmith
authors.forename: T A
authors.initials: TA
authors.lastname: Leslie
authors.forename: N A
authors.initials: NA
authors.lastname: Hayes
authors.forename: N J
authors.initials: NJ
authors.lastname: Levell
authors.forename: P M
authors.initials: PM
authors.lastname: Dowd
authors.forename: J C
authors.initials: JC
authors.lastname: Foreman
mesh_terms: D000293:Adolescent; D000328:Adult; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001808:Blood Vessels / Q000737:chemistry / Q000187:drug effects; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology; D015232:Dinoprostone; D004791:Enzyme Inhibitors / Q000032:analysis*; D004890:Erythema / Q000139:chemically induced / Q000517:prevention & control; D005260:Female; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008875:Middle Aged; D019331:NG-Nitroarginine Methyl Ester; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D011832:Radiation Injuries / Q000517:prevention & control; D012016:Reference Values; D012039:Regional Blood Flow / Q000187:drug effects; D012867:Skin / Q000098:blood supply / Q000187:drug effects* / Q000528:radiation effects; D014466:Ultraviolet Rays; D014661:Vasoconstriction / Q000187:drug effects; D019323:omega-N-Methylarginine
chemical_list: D004791:Enzyme Inhibitors; D019323:omega-N-Methylarginine; D001120:Arginine; D019001:Nitric Oxide Synthase; D015740:Calcitonin Gene-Related Peptide; D015232:Dinoprostone; D019331:NG-Nitroarginine Methyl Ester