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Ischemic shortening of action potential duration as a result of KATP channel opening attenuates myocardial stunning by reducing calcium influx

delete2002-01-01
delete27
PRE
AI
L
Lascano, EC *
N
Negroni, JA
D
del Valle, HF
DOI:10.1023/A:1016198011919delete
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Abstract

Abstract

En 中文
Action potential duration (APD) shortening due to opening of sarcolemmal ATP-dependent potassium (KATP) channels has been postulated to protect the myocardium against postischemic damage by reducing Ca2+ influx. This hypothesis was assessed, assuming that increased postischemic stunning due to KATP channel inhibition with glibenclamide could be reverted by the addition of the Ca2+ channel blocker diltiazem. Percent wall thickening fraction (% WTh, conscious sheep) and APD (open-chest sheep) were obtained from the following groups: control: 12 min ischemia by anterior descending coronary artery occlusion followed by 2 h reperfusion; glibenclamide: same as control, with glibenclamide (0.4 mg/kg) infused 30 min before ischemia; diltiazem: same as control, with diltiazem (100 mug/kg) administered prior to ischemia; glibenclamide+diltiazem: both drugs infused as in glibenclamide and diltiazem groups. APD was reduced in control ischemia. Conversely, KATP-channel blockade by glibenclamide lengthened APD and increased postischemic stunning (p<0.01 vs. control); glibenclamide+diltiazem did not shorten APD but enhanced functional recovery (p<0.01 vs. glibenclamide). Ca2+ channel blockade improvement of increased stunning provoked by KATP channel inhibition supports the hypothesis that APD shortening due to opening of KATP channels protects against postischemic stunning by limiting Ca2+ influx.
Keywords:
stunning
KATP channels
action potential duration
Ca2+ influx
conscious sheep
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Molecular and Cellular Biochemistry cover
Molecular and Cellular Biochemistry
IF:
3.7
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9.5K
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