MCI-154, a Ca2+ sensitizer, increases survival in cardiomyopathic hamsters

Cardiotonic agent SCH00013 prolongs survival of cardiomyopathic hamsters

The authors examined the effects of long-term treatment with SCH00013, a novel cardiotonic agent with calcium-sensitizing action, on survival of hereditary cardiomyopathic BIO 14.6 hamsters. Sixty-nine male hamsters at 223 days of age were divided into untreated, SCH00013-low (approximately 1 mg/kg/d), and SCH00013-high (approximately 10 mg/kg/d) groups. Survival curves were constructed in the three groups. The first deaths in the untreated, SCH00013-low, and SCH00013-high groups were found at 263, 290, and 314 days of age, respectively. A 50% mortality rate was observed at 392 days in the untreated group, 396 days in the SCH00013-low group, and 445 days in SCH00013-high group. The survival time distribution of the SCH00013-high group was significantly different from that of the untreated group (P < 0.005). However, histomorphometric examinations revealed that the degree of progression of calcification and fibrosis in the ventricular wall of the BIO 14.6 hamsters was not different between the untreated and SCH00013-treated groups. Plasma concentration of this agent was 2 microM at the end of the second week of continuous administration via drinking water in SCH00013-high group. Thus, SCH00013 was beneficial for the survival of cardiomyopathic hamsters, suggesting that this agent is a possible candidate for the treatment of chronic heart failure.

T-1032, a novel phosphodiesterase type 5 inhibitor, increases the survival of cardiomyopathic hamsters

To evaluate the influence of T-1032 (methyl2-(4-aminophenyl)-1,2-dihydro-1-oxo-7-(2-pyridylmethoxy)-4-(3,4,5-trimethoxyphenyl)-3-isoquinoline carboxylate sulfate), a potent and relatively selective phosphodiesterase 5 inhibitor, on chronic heart failure, we examined the acute hemodynamic profile of T-1032 and its chronic effect on the survival of Bio 14.6 cardiomyopathic hamsters. In the acute study, T-1032 (1, 10, 100 microg/kg) was administered intravenously by means of a dose-escalating procedure in 55-week-old hamsters. T-1032 significantly reduced both the right and left ventricular end-diastolic pressure in a dose-dependent manner. T-1032 modestly reduced the systemic arterial pressure at the highest dose (100 microg/kg i.v.). T-1032 did not change the heart rate or left ventricular dp/dt(max). In the survival study, chronic administration of T-1032 (50 and 500 ppm in a diet) increased survival, and the survival rate was 24.2%, 45.4% and 48.5% in the control, 50 and 500 ppm-treated groups, respectively. The median survival was 55, 58 and 58 weeks in control, 50 and 500 ppm-treated groups, respectively. Analysis of the survival curves revealed that T-1032 (500 ppm) significantly increased the survival of these hamsters (P<0.05 vs. control). It was concluded that T-1032 had beneficial hemodynamic effects on heart failure in Bio 14.6 cardiomyopathic hamsters, and the favorable hemodynamic changes induced by T-1032 were partly related to the increase in the survival of these hamsters. Phosphodiesterase type 5 inhibitors may have therapeutic potential for the treatment of chronic heart failure.