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Estimates of left ventricular interstitial fluid adenosine during catecholamine stimulation
J M Gidday1, H E Hill, R Rubio
1Department of Physiology, University of Virginia School of Medicine, Charlottesville 22908.
The American Journal of Physiology
|February 1, 1988
Summary
Interstitial fluid adenosine (Ado) concentrations in the heart directly influence coronary blood flow (CBF). This study validates a new method for measuring Ado, confirming its role in regulating blood flow during catecholamine stimulation.
Area of Science:
- Cardiovascular Physiology
- Biochemical Regulation
- Myocardial Metabolism
Background:
- The relationship between myocardial interstitial fluid (ISF) adenosine (Ado) and coronary blood flow (CBF) regulation is debated.
- Previous methods for measuring ISF Ado rely on assumptions that may not be valid.
Purpose of the Study:
- To validate a novel epicardial chamber (EC) method for estimating ISF Ado concentrations.
- To investigate the role of ISF Ado in mediating coronary hyperemia during catecholamine stimulation.
Main Methods:
- Utilized an epicardial chamber (EC) on the left ventricular epicardium of anesthetized dogs.
- Measured endogenous adenosine accumulation in the EC buffer to estimate ISF Ado.
- Administered intravenous catecholamines to assess effects on Ado concentrations and influx kinetics.
Main Results:
- The EC method provided direct estimates of steady-state ISF Ado concentrations (75-125 nM) within 4 minutes.
- Catecholamine infusions doubled steady-state EC Ado concentrations without altering Ado influx.
- Demonstrated ISF Ado accumulation and its role in catecholamine-induced hyperemia.
Conclusions:
- The EC technique offers a more direct estimation of myocardial interstitial fluid adenosine concentrations.
- Interstitial fluid adenosine plays a significant role in mediating the increased coronary blood flow associated with myocardial catecholamine stimulation.