Fig. 6.

Antagonism of the coronary vasoactivity of DITC-APEC (solid bar) by the administration of 0.1 mM 8-SPT (open bar). begun 20 min before and continuing throughout the administration of DITC-APEC. Each symbol represents observations in a different heart. In one heart (∇) 8-SPT lowered coronary flow (CBF) from the control level by 40%, evidence that the concentration of adenosine in the interstitial space exceeded the threshold of vasoactivity, possibly because the initial period of equilibration was not long enough. However, even in this heart 8-SPT strongly antagonized the vasoactivity of DITC-APEC