The effect of a long-acting adenosine analog on blood flow through various organs in the dog.

Radioactively labeled microspheres were used to investigate the effect of 2',3'-di-O-nitro-5'-(N-ethylcarboxamido)-adenosine (10 micrograms/kg orally), a long-acting adenosine analog, on blood flow through various organs over an experimental period of three hours in conscious dogs. There was a significant increase in myocardial, cerebral, intestinal, and renal cortical blood flow, whereas the flow through skeletal muscle, liver, pancreas, and renal medulla was unaffected. The endocardial/epicardial flow ratio, which was more than one under control conditions, decreased significantly. Arterial blood pressure and heart rate remained virtually unchanged. Since the adenosine analog is rapidly and completely denitrated in vivo, the denitration product 5'-(N-ethylcarboxamide)-adenosine, a highly potent adenosine receptor agonist, must be considered as the vasoactive metabolite.