Relationship between myocardial oxygen consumption, coronary flow, and adenosine release in an improved isolated working heart preparation of guinea pigs.

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Abstract
We describe herein an isolated working heart preparation of guinea pigs, in which coronary perfusion pressure can be varied independently from afterload by directing left ventricular stroke volume into an artificial circulation. This preparation proved to be functionally stable, exhibited hemodynamic features characteristic of the heart in situ, and shows the phenomena of flow autoregulation, reactive hyperemia, and hypoxic and metabolic vasodilation. Myocardial oxygen consumption and coronary flow were tightly coupled when cardiac work was enhanced by either 1.5-6.0 X 10(-9) M isoproterenol (r = 0.975) or changes of afterload (20-100 mm Hg) (r = 0.890). Isoproterenol-induced changes in adenosine release correlated with changes of coronary flow (r = 0.869) and myocardial oxygen consumption (r = 0.894). The concentrations of endogenously formed adenosine were within the vasodilatory range of exogenously applied adenosine. In contrast, afterload-induced changes in myocardial oxygen consumption were not asso...

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