Interaction of taurine with methionine: inhibition of myocardial phospholipid methyltransferase.
Perfusion of isolated, working rat heart with buffer containing 300 microM methionine in the presence of 2.5 U/L insulin led to a 15% decrease in cardiac work and a four-fold decrease in sarcolemmal Na(+)-Ca2+ exchange activity. These effects of methionine were largely prevented by inclusion of 10 mM taurine in the buffer supplemented with methionine and insulin. Taurine also reduced the extent of 3H-methyl group incorporation from radioactive methionine into myocardial phospholipids by approximately 45%. Assays of sarcolemmal phospholipid methyltransferase activity at catalytic sites I, II, and III revealed that taurine inhibited N-methylation activity approximately 30%. The data imply that the ability of taurine to modulate myocardial contraction and calcium transport may be related to taurine-mediated inhibition of phospholipid N-methylation.
Hamaguchi
T
T
University of South Alabama School of Medicine, Department of Pharmacology, Mobile 36688.
Azuma
J
J
Schaffer
S
S
D000818:Animals; D002118:Calcium / Q000378:metabolism; D006321:Heart / Q000187:drug effects*; D008297:Male; D008715:Methionine / Q000494:pharmacology*; D008780:Methyltransferases / Q000378:metabolism*; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013654:Taurine / Q000494:pharmacology*
D010743:Phospholipids; D013654:Taurine; D008715:Methionine; D008780:Methyltransferases; D002118:Calcium