Acidic buffer induced muscle pain evokes referred pain and mechanical hyperalgesia in humans

Laura A Frey Law; Kathleen A Sluka; Tara McMullen; Jennifer Lee; Lars Arendt-Nielsen; Thomas Graven-Nielsen

doi:10.1016/j.pain.2008.08.014

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Acidic buffer induced muscle pain evokes referred pain and mechanical hyperalgesia in humans

Journal article

Open access

Peer reviewed

Acidic buffer induced muscle pain evokes referred pain and mechanical hyperalgesia in humans

Laura A Frey Law, Kathleen A Sluka, Tara McMullen, Jennifer Lee, Lars Arendt-Nielsen and Thomas Graven-Nielsen

Pain (Amsterdam), Vol.140(2), pp.254-264

2008

DOI: 10.1016/j.pain.2008.08.014

PMCID: PMC2613646

PMID: 18835099

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http://doi.org/10.1016/j.pain.2008.08.014View

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Abstract

While tissue acidosis causes local deep-tissue pain, its effect on referred pain and mechanical muscle hyperalgesia is unknown. The aim of this study was to investigate a human experimental acidic muscle pain model using a randomized, controlled, single-blinded study design. Seventy-two subjects (36 female) participated in three visits, each involving one 15 min intramuscular infusion into the anterior tibialis muscle: acidic phosphate buffer (pH 5.2) at 40 ml/h ( N = 69) or 20 ml/h ( N = 54), normal phosphate buffer (pH 7.3) at 40 ml/h ( N = 70), or isotonic saline at 40 ml/h ( N = 19). Pain ratings and pressure sensitivity of superficial and deep tissues were assessed before, during, and 20 min after infusion. Acidic buffer produced light to moderate, rate-dependent, muscle pain (not sex-dependent) compared to the control infusions, that referred pain to the ankle in 80% of women and 40% of men. Pain did not vary across self-reported menstrual phases. Pressure pain thresholds (PPTs) were reduced over the infused muscle with acidic infusion, defined as primary mechanical hyperalgesia. PPTs decreased at the ankle in those with referred pain in response to acidic buffer, i.e. referred mechanical hyperalgesia, but not at the foot. No pain or changes in PPTs occurred in the contralateral leg. These results demonstrate muscle acidosis can lead to local and referred pain and hyperalgesia, with significant sex differences in development of referred pain.

Central sensitization

Experimental pain

Myalgia

Pressure pain thresholds

Details

Title: Subtitle: Acidic buffer induced muscle pain evokes referred pain and mechanical hyperalgesia in humans
Creators: Laura A Frey Law - Graduate Program in Physical Therapy and Rehabilitation Science, The University of Iowa, 1-252 Medical Education Building, Iowa City, IA 52242, USA
Kathleen A Sluka - Graduate Program in Physical Therapy and Rehabilitation Science, The University of Iowa, 1-252 Medical Education Building, Iowa City, IA 52242, USA
Tara McMullen - Graduate Program in Physical Therapy and Rehabilitation Science, The University of Iowa, 1-252 Medical Education Building, Iowa City, IA 52242, USA
Jennifer Lee - Graduate Program in Physical Therapy and Rehabilitation Science, The University of Iowa, 1-252 Medical Education Building, Iowa City, IA 52242, USA
Lars Arendt-Nielsen - Center for Sensory-Motor Interaction (SMI), Aalborg University, Aalborg, Denmark
Thomas Graven-Nielsen - Center for Sensory-Motor Interaction (SMI), Aalborg University, Aalborg, Denmark
Resource Type: Journal article
Publication Details: Pain (Amsterdam), Vol.140(2), pp.254-264
DOI: 10.1016/j.pain.2008.08.014
PMID: 18835099
PMCID: PMC2613646
NLM abbreviation: Pain
ISSN: 0304-3959
eISSN: 1872-6623
Publisher: Elsevier B.V
Language: English
Date published: 2008
Academic Unit: Iowa Neuroscience Institute; Nursing; Physical Therapy and Rehabilitation Science; Neuroscience and Pharmacology; Internal Medicine
Record Identifier: 9984040276202771

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