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.
McArdle
A
A
Department of Medicine, Muscle Research Centre, University of Liverpool, Liverpool L69 3GA, UK.
Khera
G
G
Edwards
R H
RH
Jackson
M J
MJ
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