DESCRIPTION (Taken from the applicant's abstract): The long-term goals are to gain a better understanding of pain associated with the musculoskeletal system and the analgesia produced by physical therapy treatments. The award will allow more research-related time to expand current and develop new collaborative efforts. These collaborative efforts will be aimed at developing new techniques (isolated primary afferent recording and push-pull perfusion), new ideas (mechanisms of analgesia produced by joint mobilization) and expanding current ideas (TENS, microdialysis, muscle hyperalgesia). Interactions with scientists from multiple basic science (Anatomy, Neurosciences, Pharmacology, Chemistry, Molecular Biology) and clinical disciplines (Physical Therapy, Internal Medicine, Anesthesia, Pathology, Chiropractic) provide an interdisciplinary perspective to the examination of musculoskeletal pain and physical therapy pain treatments. Group journal clubs and laboratory meetings are held weekly with several laboratories (Gebhart, Brennan, Hammond, Proudfit, Sluka) investigating pain. The research proposal in this application is designed to characterize a newly developed animal model of chronic pain induced by two unilateral injections of low pH saline into the gastrocnemius muscle. In the work proposed they hypothesize that the development of the long lasting bilateral hyperalgesia is dependent initially on activation of acid sensing ion channels (ASIC) from the site of injection. Activation of acid sensing ion channels results in long lasting, widespread hyperalgesia that is sustained by activation of central mechanisms in the spinal cord. These proposed studies are intended to help in the understanding and thus potential treatment of chronic muscle pain including such conditions as fibromyalgia, myofascial pain and low back pain.