Enhanced interstitial fluid adenosine attenuates myocardial stunning

Area of Science:

• Cardiology
• Pharmacology
• Biochemistry

Background:

• Myocardial stunning, a reversible dysfunction post-ischemia, is a significant clinical concern.
• Exogenous adenosine demonstrates protective effects on ischemic heart tissue.
• The role of endogenous adenosine in mitigating myocardial stunning requires further investigation.

Purpose of the Study:

• To investigate whether augmenting endogenous adenosine levels can attenuate myocardial stunning.
• To evaluate the efficacy of an adenosine deaminase inhibitor in protecting the ischemic myocardium.

Main Methods:

• Anesthetized dogs underwent 15 minutes of ischemia followed by 60 minutes of reperfusion to induce myocardial stunning.
• Erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA), an adenosine deaminase inhibitor, was administered to increase adenosine levels.
• Interstitial fluid (ISF) adenosine levels, coronary blood flow, and regional systolic wall thickening were measured and compared between EHNA-treated and untreated groups.

Main Results:

• EHNA administration significantly increased pre-ischemia ISF adenosine levels and coronary blood flow.
• EHNA treatment led to a dramatic sixtyfold increase in ISF adenosine during ischemia and reperfusion compared to a fourfold increase in the untreated group.
• Post-ischemic regional function was significantly enhanced in the EHNA-treated group.

Conclusions:

• Adenosine deaminase inhibition effectively increases ISF adenosine levels.
• Augmenting endogenous adenosine levels attenuates myocardial stunning and improves post-ischemic cardiac function.
• Metabolic manipulation of myocardial nucleoside levels offers a promising strategy for limiting post-ischemic myocardial dysfunction.