TAURINE DEPLETION, A NOVEL MECHANISM FOR CARDIOPROTECTION FROM REGIONAL ISCHEMIA

Three processes that have been implicated in ischemic injury are impai red Ca2+ movement, altered osmoregulation, and membrane remodeling. Be cause 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 r isk 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 fo und to correlate (r = 0.85) with the extent of taurine depletion, the latter dependent on the length of beta-alanine feeding. When the tauri ne-depleted rats were fed taurine, myocardial taurine levels were rest ored and the cardioprotection was lost. However, addition of neither b eta-alanine (3%) nor taurine (20 mM) to the perfusion medium altered i nfarct size. We conclude that taurine depletion renders the heart resi stant to injury caused by regional ischemia.