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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 less than 0.05), maximal rate of LV pressure rise (+dP/dtmax; 1,103 +/- 38 vs. 718 +/- 172 mmHg/s; P less than 0.05), and fall (-dP/dtmax; 930 +/- 46 vs. 587 +/- 129 mmHg/s; P less than 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.

Anophryoides haemophila is a ciliated protozoan and the causative agent of bumper car disease in lobsters. An in vitro system was developed to assess the effects of chemotherapeutants on c~liate motility and morphology. Monensin, formaldehyde and pyrimethamine + sulphaquinoxaline caused a dose-dependent reduction in ciliate motility and induced cell lysis The effects of oxytetracycline were dependent upon the incubat~on solut~on; no effect was observed on ciliates in seawater and a dose-dependent decrease in ciliate motility and cell rounding occurred in 0.8 M NaCI. Amprolium had no effect on ciliate motility or morphology. This system can be used to rapidly screen antiprotozoan compounds for efficacy against A. haemophila prior to selecting compounds for in vivo efficacy and safety studies.

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