Delayed Protective Effects of Hyperoxia Against Cardiac Arrhythmias and Infarction in Anesthetized Rats

Esmaili Dehaj, Mansour; Baharvand, Babak; Rasoulian, Bahram; Foadaddini, Mohsen; Asgari, Alireza; Noroozzadeh, Ali; Poorkhalili, Khalil; Wahhab Aghai, Hannaneh; Khoshbaten, Ali

doi:10.1016/j.jss.2007.12.802

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Volume 151, Issue 1 , Pages 55-61, January 2009

Delayed Protective Effects of Hyperoxia Against Cardiac Arrhythmias and Infarction in Anesthetized Rats

Mansour Esmaili Dehaj, Ph.D.
- Research Center for Trauma, Baqiyatallah University of Medical Sciences, Teheran, Iran
- Department of Physiology, Yazd University of Medical Sciences, Yazd, Iran
- To whom correspondence and reprint requests should be addressed at Department of Physiology, Faculty of Medicine, Baqyatallah University of Medical Sciences, P.O. Box 19395/6558, Tehran, Iran
Babak Baharvand, M.D.
- Division of Heart, Shohadaye Ashayer Hospital, Khoramabad, Iran
Bahram Rasoulian, M.D., Ph.D.
- Research Center for Trauma, Baqiyatallah University of Medical Sciences, Teheran, Iran
- Department of Physiology and Pharmacology, Lorestan University of Medical Sciences, Khoramabad, Iran
Mohsen Foadaddini, M.Sc.
- Department of Physiology and Biophysics, Baqiyatallah University of Medical Sciences, Teheran, Iran
Alireza Asgari, Ph.D.
- Physical Fitness Research Center, Baqiyatallah University of Medical Sciences, Teheran, Iran
- Department of Physiology and Biophysics, Baqiyatallah University of Medical Sciences, Teheran, Iran
Ali Noroozzadeh, M.Sc.
- Department of Physiology and Biophysics, Baqiyatallah University of Medical Sciences, Teheran, Iran
Khalil Poorkhalili, Ph.D.
- Department of Physiology, School of Medical Sciences, Tarbiat Modares University, Teheran, Iran
Hannaneh Wahhab Aghai, Ph.D.
- Department of Physiology and Biophysics, Baqiyatallah University of Medical Sciences, Teheran, Iran
Ali Khoshbaten, Ph.D.
- Research Center for Chemical Injuries, Baqiyatallah University of Medical Sciences, Teheran, Iran
- Department of Physiology and Biophysics, Baqiyatallah University of Medical Sciences, Teheran, Iran

Received 24 September 2007 published online 12 May 2008.

Background

Previous studies have shown that pretreatment with normobaric hyperoxia has cardioprotective effect in isolated rat heart. The present study was designed to test the hypothesis that pretreatment normobaric hyperoxia could induce delayed cardioprotection effect in an in vivo regional heart ischemia.

Materials and methods

Experiment 1: Rats were exposed to normobaric normoxia or to normobaric hyperoxia (O₂ > 95%) for 15, 30, 60, 120, and 180 min (H15, H30, H60, H120, and H180 groups, respectively). After 24 h, they were subjected to 30 min regional ischemia and 90 min reperfusion. Then, the hearts were harvested for measurement of infarct size. Lead II of electrocardiogram was continuously recorded for analysis of ischemic arrhythmias. Experiment 2: Different oxygen concentrations were tested in the same model of heart ischemia.

Results

Compared with normoxia group, infarct size significantly reduced in H120 and H180 groups (from 48.1 ± 4 to 31.4 ± 3.3 and 30 ± 2.4, respectively); 120 and 180 min of >95% hyperoxia significantly reduced the number of ventricular beats (from 314 ± 34.9 to 173 ± 20.3 and 178 ± 15.7, respectively) and incidence of ventricular fibrillation (from 66.8% to 30% and 22.2%, respectively). When the oxygen concentration decreased to 80%, its effect on infarct size was abolished; however, its antiarrhythmic effect persisted. Further reduction of oxygen concentration eliminated both the effects.

Conclusion

These results show that hyperoxia pretreatment may induce delayed anti-infarct and antiarrhythmic effects in anesthetized rats. These effects are dependent on the exposure time and oxygen concentration.

Key Words: hyperoxia, ischemia, reperfusion, arrhythmia, preconditioning