Program

PO4-9-19

On the benefit of melatonin in protection against ouabain-induced arrhythmia through modulation of oxidative stress factors in isolated rat atria

[Speaker] Vahid Nikoui:1
[Co-author] Fatemeh Tokazabani Belasi:2, Azam Bakhtiarian:3, Saeed Mehrzadi:1, Mohammad Yahya Karimi:1, Muhammad Imran Khan:4, Mehrdad Foroohandeh:5, Amir Rashidian:3, Roya Fallah:6, Shayan Amiri:7
1:Razi Drug Research Center, Iran University of Medical Sciences, Tehran, Iran, 2:Department of Biology, Damghan Branch, Islamic Azad University, Damghan, Iran, 3:Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran, 4:Department of Pharmacy, Kohat University of Science and Technology, 26000 Kohat, KPK, Pakistan, 5:Department of Oral Pathology, Dental School, Isfahan University of Medical Science, Isfahan, Iran, 6:Department of Cardiology, Shahid Beheshti University of Medical Sciences, Tehran, Iran, 7:Regenerative Medicine Program, Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada

Background: Melatonin is a hormone, which is shown to exert various considerable cardioprotective and antioxidant properties, and considering the involvement of oxidative stress factors in various types of cardiac arrhythmia, in the present experiment, we investigated the possible involvement of oxidative stress factors in antiarrhythmic effects of melatonin in ouabain-induced arrhythmia in isolated rat atria.
Methods: Male rats divided into two groups, receiving either of melatonin (2 mg/kg) or vehicle, orally once daily for three weeks. Rats were anesthetized, and atria were isolated incubated with ouabain in an organ bath. Time of onset of arrhythmia and asystole as well as atrial beating rate and contractile force were recorded. We also measured the activity of superoxide dismutase (SOD) and levels of thiobarbituric acid reactive substances (TBARS) in atria after injection of ouabain to animals. Unpaired Student's t-test was used to compare the time of onset of arrhythmia and asystole as well as atrial beating rate and contractile force between treatment and control groups. Paired Student's t-test was carried out to determine the effects of ouabain on atrial beating rate and contractile force within groups. One-way analysis of variance (ANOVA) followed by Tukey's post-hoc test was used to compare the atrial SOD activity and TBARS levels between groups. P<0.05 was considered statistically significant.
Results: Pretreatment of animals with melatonin could significantly postpone the onset of arrhythmia and asystole compared with vehicle-treated group (P<0.001). Incubation of ouabain boosted the atrial beating rate in vehicle-treated group (P<0.01), while this response in melatonin-treated group was not significant (P>0.05). Injection of ouabain decreased the activity of SOD and increased the levels of TBARS in atria (P<0.001, P<0.01, respectively), while pretreatment of animals with melatonin reversed these effects (P<0.05).
Conclusions: It is concluded that melatonin possesses antiarrhythmic properties, and oxidative stress factors might mediate this response.

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