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Changes in Ischemic Tolerance and Effects of Ischemic Preconditioning in Middle-aged Rat Hearts
- Source :
- Circulation. 95:2559-2566
- Publication Year :
- 1997
- Publisher :
- Ovid Technologies (Wolters Kluwer Health), 1997.
-
Abstract
- Background Although both clinical and animal studies have shown that ischemic tolerance is reduced in the senescent myocardium, it has not been clarified when myocardium becomes more vulnerable to ischemia. Preconditioning protects the hearts of young adult animals of various species, but its effects are not identical in human studies. We investigated whether ischemic tolerance and the effect of preconditioning decreased in isolated hearts of middle-aged rats. Methods and Results The hearts of young adult rats (12 weeks old: group Y, n=44) and middle-aged rats (50 weeks old: group M, n=44) were subjected to global ischemia for 15, 20, or 25 minutes followed by reperfusion. Hearts were also subjected to preconditioning and then to 20 (group Y, n=22) or 15 (group M, n=22) minutes of ischemia followed by reperfusion. Left ventricular developed pressure (LVDP) was decreased by 40% to 60%, and the level of ATP was decreased by 60% to 70% in group M compared with group Y. Preconditioning increased LVDP (% LVDP, 40.5% to 72.4%) and levels of high-energy phosphates (ATP, 11.8 to 14.1; creatine phosphate, 17.0 to 23.1 μmol/g dry wt) and reduced left ventricular end-diastolic pressure (LVEDP, 32.8 to 10.3 mm Hg), creatine kinase release (257 to 132 U/g dry wt), and ryanodine-sensitive sarcoplasmic reticulum Ca 2+ release after ischemia in group Y. Preconditioning exerted opposite effects in group M (% LVDP, 45.9% to 15.8%; LVEDP, 21.0 to 28.5 mm Hg; ATP, 14.1 to 8.5 μmol/g dry wt; and CK release, 176 to 332 U/g dry wt). Preconditioning was associated with increases in the incidence of reperfusion-induced ventricular fibrillation (0% to 62.5%) and the rate of sarcoplasmic reticulum Ca 2+ release in group M. Conclusions These results indicate that hearts became more vulnerable to ischemia with age and that the beneficial effects of preconditioning were reversed in middle-aged rat hearts.
- Subjects :
- Male
medicine.medical_specialty
Phosphocreatine
Ischemia
chemistry.chemical_element
Myocardial Reperfusion
Calcium
Creatine
Ventricular Function, Left
chemistry.chemical_compound
Adenosine Triphosphate
Physiology (medical)
Internal medicine
medicine
Animals
Creatine Kinase
biology
business.industry
Myocardium
Age Factors
Heart
medicine.disease
Rats, Inbred F344
Rats
Sarcoplasmic Reticulum
Preload
Endocrinology
chemistry
Anesthesia
Ischemic Preconditioning, Myocardial
Ventricular fibrillation
Tachycardia, Ventricular
biology.protein
Ischemic preconditioning
Creatine kinase
Energy Metabolism
Cardiology and Cardiovascular Medicine
business
Subjects
Details
- ISSN :
- 15244539 and 00097322
- Volume :
- 95
- Database :
- OpenAIRE
- Journal :
- Circulation
- Accession number :
- edsair.doi.dedup.....5211619d9884e4b4e96aec7064928677