HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free All Versions of this Article: 100/2/535    most recent 00902.2005v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Wong, B. J. Articles by Minson, C. T. Search for Related Content PubMed PubMed Citation Articles by Wong, B. J. Articles by Minson, C. T.

Minimal role for H₁ and H₂ histamine receptors in cutaneous thermal hyperemia to local heating in humans

Department of Human Physiology, University of Oregon, Eugene, Oregon

Submitted 27 July 2005 ; accepted in final form 27 September 2005

The precise mechanism(s) underlying the thermal hyperemic response to local heating of human skin are not fully understood. The purpose of this study was to investigate a potential role for H₁ and H₂ histamine-receptor activation in this response. Two groups of six subjects participated in two separate protocols and were instrumented with three microdialysis fibers on the ventral forearm. In both protocols, sites were randomly assigned to receive one of three treatments. In protocol 1, sites received 1) 500 µM pyrilamine maleate (H₁-receptor antagonist), 2) 10 mM L-NAME to inhibit nitric oxide synthase, and 3) 500 µM pyrilamine with 10 mM N^G-nitro-L-arginine methyl ester (L-NAME). In protocol 2, sites received 1) 2 mM cimetidine (H₂ antagonist), 2) 10 mM L-NAME, and 3) 2 mM cimetidine with 10 mM L-NAME. A fourth site served as a control site (no microdialysis fiber). Skin sites were locally heated from a baseline of 33 to 42°C at a rate of 0.5°C/5 s, and skin blood flow was monitored using laser-Doppler flowmetry (LDF). Cutaneous vascular conductance was calculated as LDF/mean arterial pressure. To normalize skin blood flow to maximal vasodilation, microdialysis sites were perfused with 28 mM sodium nitroprusside, and control sites were heated to 43°C. In both H₁ and H₂ antagonist studies, no differences in initial peak or secondary plateau phase were observed between control and histamine-receptor antagonist only sites or between L-NAME and L-NAME with histamine receptor antagonist. There were no differences in nadir response between L-NAME and L-NAME with histamine-receptor antagonist. However, the nadir response in H₁ antagonist sites was significantly reduced compared with control sites, but there was no effect of H₂ antagonist on the nadir response. These data suggest only a modest role for H₁-receptor activation in the cutaneous response to local heating as evidenced by a diminished nadir response and no role for H₂-receptor activation.

microdialysis; cutaneous circulation; nitric oxide; neuropeptides

This article has been cited by other articles:

				M. Shibasaki, S. Durand, S. L. Davis, J. Cui, D. A. Low, D. M. Keller, and C. G. Crandall Endogenous nitric oxide attenuates neutrally mediated cutaneous vasoconstriction J. Physiol., December 1, 2007; 585(2): 627 - 634. [Abstract] [Full Text] [PDF]

				B. L. Houghton, J. R. Meendering, B. J. Wong, and C. T. Minson Nitric oxide and noradrenaline contribute to the temperature threshold of the axon reflex response to gradual local heating in human skin J. Physiol., May 1, 2006; 572(3): 811 - 820. [Abstract] [Full Text] [PDF]