Possible involvement of alanine and pyruvate in the regulation of glucose transport in heart muscle cells.
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 transport Vmax (from 44.6 to 81.5 pmol.s-1.mg protein-1) without affecting the Km (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.
Fischer
Y
Y
Institute of Physiology, Medical Faculty, RWTH Aachen, FRG.
Rose
H
H
Kammermeier
H
H
D000409:Alanine / Q000494:pharmacology; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology; D002478:Cells, Cultured; D003847:Deoxyglucose / Q000378:metabolism*; D005260:Female; D006321:Heart / Q000187:drug effects; D007700:Kinetics; D009206:Myocardium / Q000378:metabolism*; D011773:Pyruvates / Q000494:pharmacology*; D019289:Pyruvic Acid; D051381:Rats; D011919:Rats, Inbred Strains; D012694:Serine / Q000494:pharmacology; D014633:Valine / Q000494:pharmacology
D011773:Pyruvates; D012694:Serine; D019289:Pyruvic Acid; D003847:Deoxyglucose; D014633:Valine; D000409:Alanine; D002118:Calcium