L-lactate Production Research Articles

Aerobic lactate production by mammary tissue.

Glucose uptake and L-lactate production were measured in cell, slice and intact tissue preparations of mammary glands from late-pregnant and lactating rats. The tissues showed extensive conversion of glucose into lactate in vitro, but not in vivo. Therefore aerobic lactate formation is not a normal feature of mammary tissue, but occurs in vitro as the result of some metabolic derangement.

Na + transport and impedance properties of the isolated frog gastric mucosa at different O 2 tensions

Na + was actively transported from the mucosal (secretory) to the serosal (nutritient) side of the isolated frog gastric mucosa at an O 2 tension of 300 mm Hg in the bathing solutions. At a high (700 mm Hg) and two lower (150 and 40 mm Hg) O 2 tensions no active transport of Na + was observed. Although no elution of l-lactate into the bathing solutions was detected, the appearance of two impedance loci at O 2 tensions of 300 mm Hg or lower was interpreted as evidence that the frog gastric mucosa was in a somewhat hypoxic condition when actively transporting Na +. This experimental finding may be of importance with regard to the evaluation of active transport of Na + in the isolated mammalian gastric mucosa, which was earlier found to have a considerable production of l-lactate, indicating tissue hypoxia. Active transport of Na + in the hypoxic gastric mucosa is suggested to be due to an asymmetric distribution of the Na 2+ pump, common to most cell membranes, in the acid-secreting cells.

The metabolism of the small intestine. Oxygen uptake and L-lactate production along the length of the small intestine of the rat and guinea pig

1. 1. Oxygen uptake and L-lactate production from endogenous substrates, and from added glucose or fructose, by rings cut from regions of the small intestine of the rat and guinea pig have been determined using adequate or partial oxygenation. 2. 2. Anaerobic lactate production was also determined. 3. 3. The metabolism of the intestine decreased towards the distal end in the rat but did not vary much in the guinea pig. 4. 4. Oxygen uptake by intestinal rings was not altered appreciably by added substrates. 5. 5. Rat rings formed more lactate from glucose than guinea pig rings. 6. 6. The muscle contributed only 10–20 per cent of the total metabolic activity.