|Title:||Loss of Preconditioning by Attenuated Activation of Myocardial Atp- Sensitive Potassium Channels in Eiderly Patients Undergoing Coronary Angioplasty
|Keywords:||coronary disease;ion channels;ischemia;reperfusion;AGING HEA;K+ CHANNELS||Issue Date:||2002||Journal Volume:||v.105||Journal Issue:||n.3||Start page/Pages:||334-340||Source:||CIRCULATION||Abstract:||
Backgroud-The ischemic preconditioning response among elderly patients is known to be lower than in adult patients . Since mitochondrial ATP- sensitive potassium (KATP) channels exert preconditioning effects, we undertook this study to determine whether this attenuated activation of KATP channels influences the reduced responsivebess of elderly patients to ischemic preconditioning. Methods and Results-Fifty-six patients undergoing angioplasty for a major epicardial coronary artery were randmly allocated to either an ischemic preconditioning group, a nicorandil (an agonist of KATP channels) group, or a glibenclamide (an antagonist of KATP channels), group based on their age; adult group (n=26; age,≦55 years; mean age, 45 ±5 years) and elderly groups (3=30; age ≧ 65 years; mean age 71±3years). Ischemic preconditioning with a 120-second coronary occusion sigificantly lowered the ischemic burden assessed by ST-segment shift, chest pain score, and myocardial lactate extraction ratios in the adult group. This did not occur in the elderly group. The impaired preconditioning responsiveness in the elderly patients was reversed by nicorandil administration or an ischemic period lengthened to 180 second. Hwwever, nicorandil-induced cardioprotection was abolished by administering glibenclamide in both the adult and ederly groups. Conclusions-The present study demonstrates that preconditioning significantly enhances the tolerance of the heart to subsequent ischemic in adults but not in senescent patients. Since prolonged ischemic and nicorandil are able to mimic preconditioning and can reverse impaired responsiveness, impaired preconditioning of the aged heart appears to be due to an attenuated activation of KATP channels.
|Appears in Collections:||醫學系|
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