| Autor: |
Liem, David A., te Lintel Hekkert, Maaike, Manintveld, Olivier C., Boomsma, Frans, Verdouw, Pieter D., Duncker, Dirk J. |
| Předmět: |
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| Zdroj: |
American Journal of Physiology: Heart & Circulatory Physiology; Mar2005, Vol. 288 Issue 3, pH1165-H1172, 6p, 1 Chart |
| Abstrakt: |
Clinical studies on cardioprotection by preinfact angina are ambiguous, which may involve development of tolerance to repealed episodes of ischemia Not all preconditioning stimuli use identical signaling pathways, and because patients likely experience varying numbers of episodes of preinfarct angina of different degrees and durations, it is important to know whether myocardium tolerant to a particular preconditioning stimulus can still be protected by stimuli employing alternative signaling pathways We tested the hypothesis that development of tolerance to a particular stimulus does not affect cardioprotec6on by stimuli that employ different signaling pathways. Anesthetized rats underwent classical, remote or pharmacological preconditioning. Infarct size (IS), produced by a 60-min coronary artery occlusion (CAO), was determined after 120 min of reperfusion. Preconditioning by two 15 min periods of CAO (2CAO15, an adenosine dependent stimulus) limited IS from 69 ± 2% to 37 ± 6%, but when 2CAO 15 was preceded by 4CAO15, protection by 2CAO15 was absent (IS = 68 ± 1%). This development of tolerance coincided with a loss of cardiac interstitial adenosine release, whereas two 15 min infusions of adenosine (200 μg/min iv) still elicited cardioprotection (IS = 40 ± 4%). Furthermore, cardioprotection was produced when 4CAO15 was followed by the adenosine independent stimulus 3CAO3 (IS = 50 ± 8%) or the remote preconditioning stimulus of two 15 min periods of mesenteric artery occlusion (IS = 49 ± 6%). In conclusion, development of tolerance to cardioprotection by an adenosine dependent preconditioning stimulus still allows protection by pharmacological or ischemic stimuli intervention employing different signaling pathways. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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