Inotropic interventions in the assessment of myocardial failure associated with taurine deficiency in domestic cats.

Of the amino acids that exist freely in the cytoplasm of myocardial cells, taurine is in highest concentration. While the precise physiological function of taurine in the myocardium has not be defined, taurine may have antioxidant properties8, 9, 29, modulating effects on myocardial calcium23, or a positive inotropic effect3, 32. In hearts isolated from taurine-de-pleted and control rats, Schaffer et al. 29 observed a significantly lower% recovery of mechanical performance in the depleted group than controls following ischemic-reperfusion injury. More recently, we24, 25 and others17 have reported that depletion of myocardial taurine results in cardiac dysfunction characterized by decreased left ventricular (LV) contractility, suggesting that taurine is essential to the maintenance of normal myocardial contractile function. Because taurine is an essential dietary amino acid in the domestic cat, a taurine-deficient state can be achieved in this species through restriction of dietary taurine14. In the cat dietary taurine deficiency leads to a spectrum of changes in myocardial function associated with decreased contractility24, 25. Dilated cardiomyopathy (DCM) appears to be one consequence of taurine deficiency in this species. However, not all cats maintained on taurine-deficient diets develop DCM24, 27, 30.