Activation of beta-adrenoceptors mimics preconditioning of rat-isolated atria and ventricles against ischaemic contractile dysfunction.
The effects of ischaemia and reoxygenation on cardiac contractile function can be abrogated by ischaemic preconditioning (IPC). We tested whether beta-adrenoceptor agonists could mimic IPC and whether IPC was dependent on beta-adrenoceptor activation in rat-isolated cardiac tissues. Paced left atria and right ventricular strips were set-up in Krebs solution and isometric developed tension recorded. Ischaemia was simulated by replacing with hypoxic glucose-free Krebs solution for 30 min. IPC and isoprenaline (10(-7) M) preconditioning for 10 min were examined. Developed tension post-reoxygenation was expressed as a percentage of the pre-ischaemic baseline. Recovery at 15 min was significantly increased by IPC in atria (47 +/- 4.0% vs. 29.3 +/- 1.7%, p < 0.05) and ventricles (39.0 +/- 5.2% vs. 22.4 +/- 2.8%, p < 0.05). At 60 min, isoprenaline-treated atria recovery (75.8 +/- 16.6%) was significantly (p < 0.05) greater than controls (47.9 +/- 2.3%). Propranolol (10(-6) M) abolished both effects. Therefore, both IPC and beta-adrenoceptor agonist-induced improvement of contractile recovery was propranolol-sensitive and beta-adrenoceptor-mediated.
Penson
Peter E
PE
Pharmacology Division, Welsh School of Pharmacy, Cardiff University, Cathays Park, Cardiff, CF10 3NB, UK.
Ford
William R
WR
Kidd
Emma J
EJ
Broadley
Kenneth J
KJ
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D016275:Atrial Function / Q000187:drug effects; D006325:Heart Atria / Q000187:drug effects; D019157:Ischemic Preconditioning, Myocardial; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D017202:Myocardial Ischemia / Q000503:physiopathology*; D015425:Myocardial Reperfusion; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018754:Ventricular Dysfunction / Q000503:physiopathology
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011433:Propranolol; D007545:Isoproterenol