November 17, 2010
It Takes 2: Double Detection Key For Sensing Muscle Pain
When cardiac or skeletal muscle is not receiving enough oxygen to meet metabolic demands, a person will experience pain, such as angina, chest pain during a heart attack, or leg pain during a vigorous sprint. This type of pain is called "ischemic" pain and is sensed in the body by receptors on sensory neurons. It has been suggested that lactic acid, which increases during muscle exertion under conditions where oxygen is low, is a potential mediator of ischemic pain via action at acid sensing channel #3 (ASIC3). However, the acid signal it generates is quite subtle and is unlikely to act alone.
"In our study, we examined whether other compounds that appear during ischemia might work synergistically with acid upon ASIC3," explains senior study author, Dr. Edwin W. McCleskey. "We found that another compound released from ischemic muscle, adenosine tri-phosphate (ATP), works together with acid by increasing the sensitivity of ASIC3 on sensory neurons." Importantly, ATP levels have been shown to rise rapidly outside ischemic muscle cells and synergistic action of ATP and acid has been observed in animal models of ischemia.
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