Effects of K(ATP) channel blockade by glibenclamide on the warm-up phenomenon
Summary
This summary is machine-generated.The warm-up phenomenon, a model for ischemic preconditioning, involves ATP-sensitive K+ channels. Blocking these channels with glibenclamide prevents the increased ischemic tolerance seen in sequential exercise tests.
Area Of Science
- Cardiology
- Exercise Physiology
- Molecular Medicine
Background
- The "warm-up phenomenon" describes enhanced tolerance to myocardial ischemia during a second exercise test.
- This phenomenon is considered a clinical model of ischemic preconditioning.
- ATP-sensitive K+ (K(ATP)) channels are implicated as mediators in experimental and clinical studies of ischemic preconditioning.
Purpose Of The Study
- To investigate the role of K(ATP) channels in the "warm-up phenomenon" observed during sequential exercise tests.
- To determine if K(ATP) channel blockade affects the increased ischemic tolerance seen in the second exercise test.
Main Methods
- Twenty-six patients with coronary artery disease were randomized to receive either oral glibenclamide (a K(ATP) channel blocker) or a placebo.
- Patients underwent two sequential treadmill exercise tests with a 15-minute recovery period.
- The rate-pressure product at 1.5 mm ST-segment depression was used as a measure of ischemic threshold.
Main Results
- After placebo, the rate-pressure product significantly increased during the second exercise test compared to the first (P<0.01).
- This increase in ischemic threshold was abolished in the glibenclamide group (P=ns).
- A significant drug-test interaction confirmed the effect of glibenclamide on the warm-up phenomenon (P=0.0091).
Conclusions
- Glibenclamide administration prevents the enhanced ischemic tolerance observed during the second of two sequential exercise tests.
- These findings support the role of ischemic preconditioning in the "warm-up phenomenon".
- The results suggest that ATP-sensitive K+ channels are at least partially involved in mediating this effect in the context of exercise testing.
View abstract on PubMed