Sex-specific and Exercise-acquired Cardioprotection is Abolished by Sarcolemmal Katp Channel Blockade in the Rat Heart.
From: Department of Integrative Physiology, University of Colorado at Boulder, Boulder, CO 80309, USA.
American journal of physiology. Heart and circulatory physiology
- Publish Date: May 2007
- ISSN: 0363-6135
- Volume: 292
- Issue: 5
- Pages: H2432-7
- Medium: Print
- Language: English
- Citation (JAMA): Chicco Adam J, Johnson Micah S, Armstrong Casey J, et al. Sex-specific and Exercise-acquired Cardioprotection is Abolished by Sarcolemmal Katp Channel Blockade in the Rat Heart.. Am. J. Physiol. Heart Circ. Physiol. May 2007;292:H2432-7
Abstract
The present study was conducted to determine whether the infarct sparing effect of short-term exercise is dependent on the operation of the myocardial sarcolemmal ATP-sensitive K(+) (K(ATP)) channel. Adult male and female Sprague-Dawley rats were exercised on a motorized treadmill for 5 days. Twenty-four hours following the training or sedentary period, hearts were isolated and exposed to 1 h of regional ischemia followed by 2 h of reperfusion on a modified Langendorf apparatus in the presence or absence of the sarcolemmal K(ATP) channel antagonist HMR-1098 (30 microM). Following the ischemia-reperfusion protocol, infarct size was determined as a percentage of the total ischemic zone at risk (ZAR). Short-term exercise reduced infarct size by 24% in males (32 +/- 2% of ZAR; P < 0.01) and by 18% in females (26 +/- 2% of ZAR; P < 0.05). Sarcolemmal K(ATP) channel blockade abolished the training-induced cardioprotection in both males and females, increasing infarct size to 43 +/- 3% and 52 +/- 4% of ZAR, respectively. In the absence of HMR-1098, infarct size was significantly lower in sedentary females than in males (33 +/- 4% vs. 42 +/- 2% of ZAR, respectively; P < 0.01). However, the presence of HMR-1098 abolished this sex difference, increasing infarct size by 58% in the sedentary females (P < 0.01) but having no effect on infarct size in sedentary males. This study demonstrates that the sex-specific and exercise-acquired resistance to myocardial ischemia-reperfusion injury is dependent on sarcolemmal K(ATP) activity during ischemia.
Mesh Headings (Keywords): Animals, Benzamides, Exercise Therapy, Female, Heart, Male, Myocardial Reperfusion Injury, Physical Conditioning, Animal, Potassium Channels, Rats, Rats, Sprague-Dawley, Sex Factors, Treatment Outcome
Check for Full Text / PubMed Unique Identifier (PMID): 17237239
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