Anti-Arrhythmic Effects of Linalool via Cx43 Expression in a Rat Model of Myocardial Infarction

BACKGROUND

Lavender is a traditional therapy for different heart symptoms including palpitation, which comprises an important symptom of cardiac arrhythmias. This experiment was designed to evaluate the antiarrhythmic effects of linalool using an experimental model of arrhythmia following myocardial infarction in rats. The underlying electrophysiological mechanism through cardiac connexin 43 (Cx43) expression was also investigated.

METHODS

Fifty male Sprague-Dawley rats were divided into five equal groups. The first group was considered as the normal control group; MI was induced by ligation of the left anterior descending artery (LAD) in the second group. The other three groups received metoprolol (100 mg/kg/day) or linalool (50 or 100 mg/kg/day) for seven days before LAD ligation. The arrhythmia score, isolated myocyte resting potential, histological changes, and cardiac Cx43 expression levels were evaluated.

RESULTS

In the MI group, there was a significant increase in the arrhythmia score but a marked decrease in resting membrane potential relative to the control; these changes were prevented by the administration of metoprolol or linalool. The histological changes were also minimized in the groups treated with these substances compared to the untreated MI group. The western blot and real-time PCR results showed that the protein expression of Cx43 in the infarct zone of the rat hearts was significantly higher in the MI groups receiving metoprolol or linalool compared with the untreated MI group.

CONCLUSION

Linalool was shown to be able to dose-dependently decrease the incidence of arrhythmias in a rat model of myocardial infarction. We propose that the key mechanism behind this antiarrhythmic effect is probably the prevention of decreased Cx43 expression following MI.

Extract from Teucrium polium L. Protects Rat Heart against Oxidative Stress Induced by Ischemic-reperfusion Injury

Background

The deleterious effect of oxidative stress on myocardial ischemia-reperfusion (I/R) has already been shown in previous studies. Since Teucrium polium has anti-oxidative and cardio-protective properties, the aim of this study was to investigate the effects of this plant on I/R injuries in the isolated rat heart.

Materials and Methods

The myocardial I/R injury of rat was created by Langendorff retrograde perfusion technology. The heart was preperfused with Krebs-Henseleit (K-H) solution containing T. polium extract for 20 min before 20 min global ischemia, and then the reperfusion with K-H bicarbonate buffer was conducted for 40 min. The left ventricular developed pressure and the maximum up/down rate of the left ventricular pressure (±dp/dt_max) were recorded by physiological recorder as the myocardial function. Lactate dehydrogenase (LDH) and creatine kinase (CK) activities in the effluent were measured to determine the myocardial injury degree. Thiobarbituric acid reactive substances (TBARS), total thiol groups (-SH), superoxide anion dismutase (SOD), and catalase (CAT) in myocardial tissue were detected to determine the oxidative stress degree.

Results

The results showed that the pretreatment with T. polium significantly enhanced cardiac parameters and the coronary artery flow, decreased the LDH, CK activities, and TBARS level, whereas it increased - SH groups, SOD and CAT activities.

Conclusions

Our findings indicated that T. polium could provide protection for heart against the I/R injury which may be related to the improvement of myocardial oxidative stress states.