In vivo microdialysis-A technique for analysis of chemical activators of muscle pain.
The accurate measurement of the chemical activators of pain in skeletal muscle has proved to be a major challenge. This study examined the applicability of microdialysis to the measurement of pain-producing substances in skeletal muscle using a defined model of ischemia and reperfusion in the rat. Microdialysis probes were placed into muscle of anesthetized rats. Ischemia was induced for 4 h, followed by reperfusion for 1 h. Perfusates were analyzed for hypoxanthine, potassium, prostaglandin (PG) E(2) and histamine. A 20-fold increase in perfusate hypoxanthine concentration was seen prior to reperfusion (70.1 +/- 27.1 microM for ischemic versus 3.7 +/- 1.9 microM for control; P < 0.05). An initial increase in PGE(2) concentration was seen during ischemia (7.4 +/- 2.0 nM versus 3.4 +/- 1.4 nM; P < 0.05) and immediately post-reperfusion (17.9 +/- 5.2 nM versus 4.0 +/- 1.1 nM; P < 0.05). Potassium concentration was significantly increased following occlusion and reperfusion. This indicates the applicability of microdialysis to the measurement of pain-producing substances in muscle during ischemia and reperfusion. Further use will provide novel information on muscle pain both in defined model systems and in clinical situations in humans.
Department of Medicine, Muscle Research Centre, University of Liverpool, Liverpool L69 3GA, UK.
A
A
McArdle
G
G
Khera
R H
RH
Edwards
M J
MJ
Jackson
D000818:Animals; D017551:Microdialysis; D009132:Muscles / Q000378:metabolism* / Q000503:physiopathology*; D009475:Neurons, Afferent / Q000378:metabolism / Q000502:physiology; D010146:Pain / Q000378:metabolism* / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar