Medical Journal of the Islamic Republic Of Iran
مجله پزشکی جمهوری اسلامی ایران
Med J Islam Repub Iran
Medical Sciences
http://mjiri.iums.ac.ir
2
journal2
1016-1430
2251-6840
8
10.18869/mjiri
14
8888
13
en
jalali
1378
11
1
gregorian
2000
2
1
13
4
online
1
fulltext
en
HYPOVENTILATION PRIOR TO ISCHEMIA PRECONDITIONS RAT MYOCARDIUM
Pharmacology
Pharmacology
Original Research: Basic Science in Medicine
Original Research: Basic Science in Medicine
Repetitive episodes of brief regional ischemia have been shown to reduce the severity
of life-threatening ventricular anhythrnias and infarct size that occur during prolonged
occlusion of the coronary artery. This phenomenon is known as ischemic preconditioning.
During studies in anesthetized, open chest Wistar rats, we accidentally observed that
poorly ventilated animals had a reduced severity of ischemic arrhythmias. Therefore, we
wished to (1) find out whether acute hypoventilation prior to coronary ligation affords
protection to the ischemic rat hearts, and (2) to evaluate the effect of recovery period of
normoventilation between hypoventilation and prolonged ischemia on the degree of
protection. Male Wistar rats were anesthetized and prepared for left coronary artery
ligation. Following a left thoracotomy, artificial respiration was immediately started with
room air of 1.5 mLll00g and 54 strokes/min. Analysis of ventricular anhythrnias during
30 min occlusion was performed. In some experiments 30 min. sustained ischemia
followed by 2 hours reperfusion and then the percentage of infarct size was measured. The
reduction of volume of ventilation to 1.1 and 0.7 mL/l00g only for 10 min immediately
prior to coronary artery occlusion resulted in a marked decrease (p<0.01) in the total
number of ventricular ectopic beats from 1336±100 in control to 485 ±75 and 328±51,
respectively, mainly by reduction of beats occurring as ventricular tachycardia (VT).
Also, the time spent in VT and in reversible ventricular fibrillation was reduced
significantly (p<0.01 and p<O.OOI, respectively). There was no mortality in animals
subjected to hypoventilation, while 33% of control rats died due to irreversible VF.
Hypoventilation also limited the infarct size very considerably (p<0.0 1) from 43.4 ±2.9%
in control animals to 12.1 ± 1 % and 9.1 ±2.9% in hypoventilated rats. The presence of an
intervening period of normoventilation between hypoventilation and prolonged ischemia
did not affect the antianhythrnic effect of hypoventilation but abolished the protective
effects of hypoventilated preconditioning against the infarction. These results may
suggest that the heart can be preconditioned by hypoventilation prior to prolonged
ischemia despite the lack of an intervening period of normoventilation.
Hypoventilation, Preconditioning, Myocardial ischemia, Arrhythmia, Infarction.
297
303
http://mjiri.iums.ac.ir/browse.php?a_code=A-10-298-378&slc_lang=en&sid=1
A
GARJANI
20031947532846004555
20031947532846004555
Yes
From the Department of Pharmacology, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz-51664, I.R.lran.
N
MALEKI
20031947532846004556
20031947532846004556
No
A
MAHDINIA
20031947532846004557
20031947532846004557
No
H
BABAEI
20031947532846004558
20031947532846004558
No