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Persistent coronary vasodilation during long-term, supramaximal doses of adenosine
The American Journal of Physiology
|November 1, 1984
Summary
Coronary circulation remains sensitive to adenosine, even with prolonged high doses. This suggests endogenous adenosine plays a key role in maintaining coronary vasodilation during increased heart energy demands.
Area of Science:
- Cardiovascular Physiology
- Pharmacology
Background:
- Skeletal muscle circulation shows tachyphylaxis to adenosine, questioning its role in metabolic control.
- The coronary circulation's response to prolonged adenosine infusion is not well understood.
Purpose of the Study:
- To investigate if the coronary circulation develops tachyphylaxis to adenosine.
- To determine if coronary vasodilation remains sensitive to other metabolic vasodilators during adenosine infusion.
Main Methods:
- Adenosine was infused into the left anterior descending coronary artery (LAD) of anesthetized dogs for 3 hours.
- Coronary blood flow, myocardial oxygen consumption, and cardiac function were measured.
- Radioactive microspheres and ultrasonic crystals were used for regional blood flow and segment shortening measurements.
Main Results:
- Coronary blood flow significantly increased with adenosine and remained elevated throughout the 3-hour infusion.
- No significant difference was observed in blood flow between early and late stages of adenosine infusion.
- Adenosine did not affect myocardial oxygen consumption or cardiac contractility.
Conclusions:
- The canine coronary circulation exhibits persistent vasodilation to sustained, high-dose adenosine.
- These findings support a role for endogenous adenosine in maintaining coronary vasodilation during increased myocardial energy demands.
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