S. Punna et al., EFFECT OF TAURINE AND METHIONINE ON SARCOPLASMIC RETICULAR CA2+ TRANSPORT AND PHOSPHOLIPID METHYLTRANSFERASE ACTIVITY, Journal of cardiovascular pharmacology, 24(2), 1994, pp. 286-292
Perfusion of rat hearts with buffer containing 300 mu M L-methionine l
ed to a decrease in Ca2+-induced Ca2+ release in sarcoplasmic reticulu
m (SR) but an increase in calcium-independent Ca2+ release from juncti
onal SR. These effects of L-methionine were not altered by exposure of
the hearts to high levels of extracellular taurine, but changes in th
e size of the intracellular taurine pool appear to modulate calcium tr
ansport in SR through two mechanisms. First, millimolar concentrations
of taurine can directly promote release of calcium from Ca-45(2+)- lo
aded junctional SR vesicles. Second, taurine serves as an inhibitor of
SR phospholipid methyltransferase, an enzyme that appears to be respo
nsible for methionine-mediated loss in Ca22+-induccd Ca2+ release acti
vity and promotion of Ca2+-independent Ca2+ release. The data imply th
at modulation of the intracellular taurine pool may affect cellular ca
lcium homeostasis and myocardial contractile function. This may be imp
ortant in development of the cardiomyopathy linked to taurine deficien
cy.