The relationship between the transport of glucose and cations across cell membranes in isolated tissues II. Effects of K+-free medium, ouabain and insulin upon the fate of glucose in rat diaphragm

Abstract

• 1.

  1. Incubation of isolated rat hemidiaphragm in a K⁺-free bicarbonate buffer has been shown to induce stimulation of glycogen synthesis and inhibition of lactate production, without change in glucose uptake.

• 2.

  2. Essentially similar changes were produced when ouabain was added to bicarbonate buffer with a normal K⁺ content.

• 3.

  3. These metabolic changes were therefore considered as secondary to a decrease in active cation transport.

• 4.

  4. Insulin (0.1 I.U./ml) was shown to stimulate glycogen synthesis, lactate production and glucose uptake.

• 5.

  5. In the presence of insulin (0.1 I.U./ml), the addition of ouabain gave a further stimulation of glycogen synthesis. This was accompanied by a decrease in lactate production and a slight depression of the glucose uptake.

• 6.

  6. Furthermore, it was shown that ouabain in concentrations down to 1.4·10⁻⁶ M induced an inhibition of CO₂ production from glucose.