Inosine monophosphate production is proportional to muscle force in vitro.

An in vitro system of muscle stimulation has been developed that combines physiologic measurements with biochemical evaluation. In the rat epitrochlearis muscle, 2 minutes of stimulation at 4 Hz results in a marked elevation of inosine monophosphate (IMP) levels. The amount of IMP generated is proportional to the amount of force developed. Depriving the muscle of oxygen results in an increased amount of IMP generation. This model provides direct confirmation of similar findings in the human forearm exercise test.