Lactate metabolism of contracting dog skeletal muscle in situ.

STAINSBY, WENDELL N., AND HUGH G. WELCH. Lactate metabolism of contracting dog skeletal muscle in situ. Am. J. Physiol. III(I): 177-183. 1966. -These experiments were designed to quantitate the lactate production by in situ skeletal muscle at various steady work rates. The gastrocnemius-plantaris muscle group and the lower leg (foot excluded) of the dog were used. Venous outflow and arterial and venous concentrations of lactate and oxygen were measured. The muscle contractions were maximal single twitches in response to supramaximal stimuli applied to the distal stump of the cut sciatic nerve. Work rate was varied by changing the twitch rate over a range of 0.5-10 twitches/set. Oxygen uptake increased with increasing twitch rate reaching 30 times resting at 3/set. Increasing the twitch rate beyond 3/set did not further increase oxygen uptake. Resting muscle usually produced a small amount of lactate. After the contractions began, lactate production increased transiently and then decreased as the contractions continued. About half the muscle preparations studied showed lactate uptake, which occurred at all twitch rates studied after 10-60 min of contractions.