Possible involvement of alanine and pyruvate in the regulation of glucose transport in heart muscle cells

Authors:
  • HRH Rose
    H Rose
  • HKH Kammermeier
    H Kammermeier
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Abstract
In isolated rat heart muscle cells, addition of L‐alanine (1.5 mmol/l) or of L‐valine (3 mmol/l) resulted in either a ca 1.5‐ or 1.3‐fold increase in glucose transport, resp. half‐maximal stimulation was observed in the presence of L‐alanine, but not of L‐valine. within a physiological plasmatic range of concentrations. D‐Alanine (1.5 mmol/l) was ineffective and the stimulating effect of L‐alanine could be prevented by an excess of L‐serine (15 30 mmol/l). L‐Alanine produced an increase in 3‐O‐methyl‐D‐glucose transportVmax(from 44.6 to 81.5 pmols−1mg protein−1) without affecting theKm(12.2 in control vs 12.8 mmol/l in alanine‐treated cells). Pyruvate (1.5 mmol/l) inhibited glucose transport by 20% and prevented the stimulating action of L‐alanine (1.5 mmol/l). These results suggest that the effect of L‐alanine in cardiac myocytes occurs through the interaction with an intracellular site and that both alanine and pyruvate may play a role in the regulation of glucose transport in these cells.

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