SYSTOLIC AND DIASTOLIC DYSFUNCTION OF THE LEFT-VENTRICLE INDUCED BY DIETARY TAURINE DEFICIENCY IN CATS

Isovolumic left ventricular (LV) preparations were used to assess myocardial failure associated with dietary taurine deficiency in cats. Adult female cats (n = 12) were fed a purified diet devoid of taurine for 6-8 mo. Six of the cats received 1,000 mg of crystalline taurine orally once daily. The remaining six cats were not provided taurine replacement. Compared with control preparations, hearts isolated from taurine-deficient cats generated significantly lower values for developed LV systolic pressure (107 +/- 6 vs. 66 +/- 15 mmHg; P < 0.05), maximal rate of LV pressure rise (+ dP/dt(max); 1,103 +/- 38 vs. 718 +/- 172 mmHg/s; P < 0.05), and fall (- dP/dt(max); 930 +/- 46 vs. 587 +/- 129 mmHg/s; P < 0.05). LV function curves generated by hearts from taurine-deficient cats were shifted downward and to the right of control curves, demonstrating inotropic depression. In addition, end-diastolic pressure-volume (compliance) relationships in hearts from taurine-deficient cats were shifted downward and to the right of controls in the direction of increased chamber compliance or distensibility. Ten millimolar taurine significantly improved inotropic indexes only in hearts from taurine-deficient cats but failed to affect diastolic compliance. Myocardial contractile dysfunction and LV chamber dilatation in hearts from taurine-deficient cats verify a causal association between dietary deficiency of this amino acid and dilated cardiomyopathy in this species.