Taurine depletion, a novel mechanism for cardioprotection from regional ischemia.

Three processes that have been implicated in ischemic injury are impaired Ca2+ movement, altered osmoregulation, and membrane remodeling. Because the amino acid, taurine, affects all three processes, it seemed logical that changes in the myocardial content of taurine might affect ischemic injury. To test this hypothesis, infarct size and areas at risk were compared in isolated hearts from control and taurine-depleted rats after a 45-min ligation of the left anterior descending coronary artery and 2 h of reperfusion. Hearts of rats treated for 4 wk with the taurine inhibitor, beta-alanine, exhibited a 57% reduction in the infarct size-to-risk area ratio. The degree of cardioprotection was found to correlate (r = 0.85) with the extent of taurine depletion, the latter dependent on the length of beta-alanine feeding. When the taurine-depleted rats were fed taurine, myocardial taurine levels were restored and the cardioprotection was lost. However, addition of neither beta-alanine (3%) nor taurine (20 mM) to the perfusion medium altered infarct size. We conclude that taurine depletion renders the heart resistant to injury caused by regional ischemia.