Differential effects of four xylidine derivatives in the model of ischemia- and re-perfusion-induced arrhythmias in rats in vivo

Rat Models of Ventricular Fibrillation Following Acute Myocardial Infarction

A number of animal models have been designed in order to unravel the underlying mechanisms of acute ischemia-induced arrhythmias and to test compounds and interventions for antiarrhythmic therapy. This is important as acute myocardial infarction (AMI) continues to be the major cause of sudden cardiac death, and we are yet to discover safe and effective treatments of the lethal arrhythmias occurring in the acute setting. Animal models therefore continue to be relevant for our understanding and treatment of acute ischemic arrhythmias. This review discusses the applicability of the rat as a model for ventricular arrhythmias occurring during the acute phase of AMI. It provides a description of models developed, advantages and disadvantages of rats, as well as an overview of the most important interventions investigated and the relevance for human pathophysiology.

New approach to molsidomine active metabolites coming from the results of 2 models of experimental cardiology

Molsidomine is a well-known vasodilatating, antianginal drug. Despite earlier studies with its metabolites (3-morpholino-syndnonimine (SIN-1) and N-nitroso-N-morpholino-amino-acetonitrile (SIN-1A)), which indicated a potential favorable cardioprotective activity, a lot of controversy remains. The aim of our research was to compare molsidomine, SIN-1, SIN-1A, and lidocaine influence on arrhythmias and hemodynamic parameters in 2 experimental models in rats. In the Langendorff heart study, SIN-1A markedly elevated left ventricular systolic pressure, maximum rise and fall of the first pressure derivative, coronary flow, and myocardial oxygen consumption. In addition, SIN-1A more so than SIN-1 significantly lowered creatine kinase release. The antiarrhythmic action of SIN-1 was observed, while lidocaine significantly diminished ventricular arrhythmias duration in comparison with the control. In the ischemia-reperfusion-induced arrhythmias model, hypotensive action of molsidomine was observed as well as the reduction in pressure rate product. Molsidomine also prolonged ventricular tachycardia duration. On the other hand, no significant effects on hemodynamic parameters as well as on ventricular arrhythmias were found in any of the SIN-1 and SIN-1A groups. In conclusion, our research suggests a possible direct, cardioprotective action of SIN-1A. It seems worthwhile to further investigate molsidomine derivatives, especially SIN-1A, because of its potential use in invasive cardiology procedures such as percutaneous transluminal coronary angioplasty.

Differential effects of furnidipines' metabolites on reperfusion-induced arrhythmias in rats in vivo

We previously established that furnidipine (FUR) and oxy dihydropyridines prevent rats mortality by strong reduction of the lethal arrhythmias in reperfusion. Therefore we decided to study the influence of three main metabolites (M-2, M-3, M-8) of FUR on ischemia-and reperfusion- induced arrhythmias and hemodynamic parameters in rat model to examine their independent activity. The metabolites (M-2, M-3, M-8) were given orally 20 mg/kg (24 and 1 h before ischemia). Mortality was significantly diminished in M-2 and M-3 treated groups with M-3 preventing animal mortality entirely. All three examined substances significantly reduced the duration and incidence of ventricular fibrillation (VF) with M-3, once again, completely preventing VF. Moreover, only M-3 significantly decreased the duration of ventricular tachycardia but had no influence on their incidence. Through the occlusion and reperfusion periods, M-2 and M-3 were markedly less hypotensive than M-8 and did not influence on heart rate. We conclude that two tested metabolites of FUR, M-3 and M-2 exhibited the most pronounced anti-arrhythmic effect being at the same time the most normotensive and therefore caused the most beneficial effects.

Protective effects of saffron (Crocus sativus) against lethal ventricular arrhythmias induced by heart reperfusion in rat: a potential anti-arrhythmic agent

CONTEXT

Saffron (Crocus sativus L.) has been used as a cuisine spice in eastern and western societies for thousands of years. In traditional medicine, saffron is recommended for the treatment of various kinds of disorders including heart palpitations.

OBJECTIVE

We investigated the hypothesis of the protective effect of saffron on lethal cardiac arrhythmias induced by heart ischemia-reperfusion in rat.

MATERIALS AND METHODS

Animals were divided into a control (CTL) group that received tap water, Saf50, Saf100 and Saf200 groups that were orally treated with aqueous extracts of saffron, at dosages of 50, 100 and 200 mg/kg/day, respectively, and amiodarone (Amio) group that orally received 30 mg/kg/day for seven days. On day 8, heart ischemia-reperfusion was induced by ligation and releasing of the left anterior descending coronary artery.

RESULTS

During reperfusion, the numbers and durations of ventricular fibrillation (VF) decreased in all groups compared to the CTL group (p < 0.05). Ventricular tachycardia (VT)/VF numbers (3.2 ± 1.2), durations (4.9 ± 2.6) and also arrhythmia severity (1.9 ± 0.35) were decreased significantly in the Saf100 group versus CTL group values (18.4 ± 11.6, 52 ± 31 and 3.3 ± 0.3, respectively). The PR and QTcn intervals of ECG were significantly longer in the Saf200 group (p < 0.001 versus CTL). The other doses of saffron only significantly prolonged the QTcn interval.

CONCLUSION

The results suggest that pretreatment with saffron, especially at the dosage of 100 mg/kg/day, attenuates the susceptibility and incidence of fatal ventricular arrhythmia during the reperfusion period in the rat. This protective effect is apparently mediated through reduction of electrical conductivity and prolonging the action potential duration.