Comparison of the Effect of Prostaglandin E(1), Prostacycline and Adenosine on Peripheral Vascular Resistance.

Prostacycline, prostaglandin E(1), and adenosine are highly effective vasodilators. These three drugs are widely used in the treatment of peripheral arterial occlusive disease. The aim of the study was to compare the vasodilatory potency of these substances in the isolated perfused guinea pig hind limb. After equilibration with Tyrode's solution and precontraction with noradrenaline 3µM, prostaglandin E(1) and adenosine were administered at dosages of 0.1, 0.3, and 1µM, whereas prostacycline was administered at a dosage of 0.01, 0.03 and 0.1µM. 0.01µM prostacycline, 0.1 µM prostaglandin E(1), and 0.1µM adenosine were the lowest dosages at which a significant vasodilation could be reached for each substance. The reduction of peripheral vascular resistance at comparable dosages of 0.1µM was 11.0 +/- 2.6% (x +/- SEM, n = 5) for adenosine, 12.0 +/- 1.0% (n = 5) for prostaglandin E(1), but 28.0 +/- 9.3% (n = 5) for prostacycline (p < 0.05 versus adenosine and prostaglandin E(1)). Even at a dosage of 0.01 µM prostacycline, a comparable reduction in peripheral vascular resistance (16.0 +/- 2.8%) could be reached, compared to a ten-fold higher dosage of prostaglandin E(1) and adenosine. At the highest concentration of 1 µM, the vasodilatory effect of adenosine was significantly less expressed, compared to that of prostaglandin E(1) (18.0 +/- 3.4% versus 33.0 +/- 4.7%). In summary, prostacycline, at a ten-fold lower concentration, showed comparable vasodilatory effects to adenosine and prostaglandin E(1). The rank order at the vasodilatory potency is prostacycline > prostaglandin E(1) > adenosine.