Fig. 3.
Adenosine (Ado) transport and transformation in isolated, perfused rabbit (left) and guinea pig (right) heart. Top panels: normalized outflow dilution curves for [14C]Ado and the 2 reference tracers, 131I-albumin (intravascular) and [3H]AraH (extracellular); model solutions are shown by lines. Bottom panels: semilog plot of Ado and its metabolites, Ino, hypoxanthine (Hx), xanthine (Xa), and uric acid (UA), in the outflow. The Ado curve is the same as in panel above. Linesjoin data points and are not model solutions. Note striking difference in shapes of effluent curves for metabolites in the 2 species. Curves labeled UA and Xa from the rabbit (bottom left) are not quantifiable, isotope count rates being 10−5 times those of albumin curve.