EFFECT OF ATP CYCLIC AMP ADENOSINE AND DIPYRIDAMOLE ON ISOLATED HELICAL STRIPS FROM PORTAL VEIN RENAL AND CORONARY ARTERIES

1. Responses to adenosine, AMP and ATP were studied in isolated helical strips of renal and coronary arteries. The three substances caused relaxation of the strips, the degree of which was dependent on the concentration of the substance in the bath. Only adenosine produced a greater relaxation (in milligram per milligram helical strip) in strips of coronary arteries as compared to renal artery strips. 2. In equimolar concentrations, the relaxing effect of ATP on helical strips of coronary arteries was twice that of either adenosine or AMP. 3. Dipyridamol caused relaxation of renal and coronary artery strips. No significant difference in the degree of relaxation between the two different arteries was observed. 4. The relaxation of strips from coronary and renal arteries caused by adenosine and dipyridamol was virtually independent of α- and β-adrenergic blockade. 5. Adenosine and dipyridamol produced contractions of isolated longitudinal portal vein strips. The strongest effect was observed when the two drugs were administered simultaneously. Concomitant with the increase in tension the frequency of the spontaneous mechanical activity increased. © 1968 Springer-Verlag.