monensin and Heart-Diseases

To compare cardiac troponin I (cTnI) concentrations determined by use of a point-of-care analyzer with values determined by use of a bench-top immunoassay in plasma samples obtained from clinically normal horses with and without experimentally induced cardiac disease, and to establish a reference range for plasma equine cTnI concentration determined by use of the point-of-care analyzer.. 83 clinically normal horses, 6 of which were administered monensin to induce cardiac disease.. A blood sample was collected from each of the 83 clinically normal horses to provide plasma for analysis by use of the point-of-care analyzer; some of the same samples were also analyzed by use of the immunoassay. All 83 samples were used to establish an analyzer-specific reference range for plasma cTnI concentration in clinically normal horses. In 6 horses, blood samples were also collected at various time points after administration of a single dose of monensin (1.0 to 1.5 mg/kg) via nasogastric intubation; plasma cTnI concentration in those samples was assessed by use of both methods.. The analyzer-specific reference range for plasma cTnI concentration in clinically normal horses was 0.0 to 0.06 ng/mL. Following monensin treatment in 5 horses, increases in plasma cTnI concentration determined by use of the 2 methods were highly correlated (Pearson correlation, 0.83). Peak analyzer-determined plasma cTnI concentrations in monensin-treated horses ranged from 0.08 to 3.68 ng/mL.. In horses with and without experimentally induced cardiac disease, the point-of-care analyzer and bench-top immunoassay provided similar values of plasma cTnI concentration.

Topics: Animals; Female; Heart Diseases; Horse Diseases; Horses; Ionophores; Male; Monensin; Point-of-Care Systems; Troponin I

A large animal with diminished cardiac function would be desirable for chronic testing of pathophysiologic responses to many human-sized devices and other therapies, especially if this model did not require prior surgical interventions or extensive technical skill and expense. Overdoses of monensin, widely used in the cattle industry as a growth promotant, are cardiotoxic, suggesting its possible use in creating cardiomyopathy. We gave a single oral dose of monensin (20 to 40 mg/kg) to 13 calves (55 to 90 kg) to produce diminished cardiac function. Hemodynamics and cardiac geometry were monitored for as long as 21 days postinduction. Within 3 days, there were signs of decreased cardiac function, as evidenced by a 10- to 20-mm Hg decrease in peak systolic blood pressure (P < 0.01 versus baseline) and a 2- to 9-mm Hg increase in central venous pressure (P < 0.01 versus baseline). There was a trend towards an increase in left ventricular end-systolic lumen diameter. Compared with those of similar-sized normal animals, stroke volume was 42% lower (P < 0.05), left atrial pressure was 67% higher (P < 0.01), and end-diastolic left ventricular pressure was 143% higher (P < 0.05). Histopathologic analysis showed extensive cardiomyocyte death. These results suggest that monensin could provide a simple, noninvasive, inexpensive, and likely irreversible means of producing clinically relevant diminished cardiac function in a human-sized animal model.

Topics: Administration, Oral; Animals; Cattle; Disease Models, Animal; Heart Diseases; Hemodynamics; Hypertrophy, Left Ventricular; Ionophores; Male; Monensin; Myocytes, Cardiac

Monensin, a well-known ionophore antibiotic, may cause severe damage in myocardial cells. We investigated whether IRFI 042, a new analogue of vitamin E, may block lipid peroxidation in myocardial cells and in turn protect against monensin toxicity. Monensin toxicity was induced by repeated daily administration of the ionophore antibiotic (150 mg/kg/day for 7 days). Sham animals received by oral gavages only a saline solution and were used as controls. All animals were randomized to receive concomitantly by oral gavages IRFI 042 (20 mg/kg) or its vehicle. The experiment lasted 8 days. Survival rate, heart lipid peroxidation, studied by means of thiobarbituric acid-reactive substances (TBARs) levels, cardiac expression of endothelial nitric oxide (e-NOS) and histological analysis of the heart were performed. Monensin administration caused a decrease in survival rate. Mortality appeared following the second monensin injection and at day 7 caused a survival rate of 20%. Thereafter, no further mortality was observed. IRFI 042 administration improved survival rate. Injection of the ionophore antibiotic resulted in a marked cardiac lipid peroxidation and in a significant reduction in cardiac e-NOS message and protein expression. IRFI 042 decreased heart TBARs levels (Monensin + vehicle = 6.5 +/- 0.8 nmol/mg; Monensin + IRFI 042 = 3.2 +/- 1.1 nmol/mg; P < 0.001) and increased e-NOS message and protein expression. Histological analysis showed that IRFI 042 improved myocardial cells damage and enhanced the depressed e-NOS expression in chick heart samples following monensin administration. Our data suggest that IRFI 042 is a promising drug to reduce monensin cardio-toxicity in chicks.

Topics: Animals; Benzofurans; Blotting, Western; Chickens; Coccidiostats; Heart; Heart Diseases; Immunohistochemistry; Lipid Peroxidation; Male; Monensin; Myocardium; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Reverse Transcriptase Polymerase Chain Reaction; RNA; Survival Analysis; Thiobarbituric Acid Reactive Substances