Comparison of the effect of prostaglandin E₁, prostacycline and adenosine on peripheral vascular resistance

Abstract

Prostacycline, prostaglandin E₁, 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 E₁ 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 E₁, 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 E₁, but 28.0 ± 9.3% (n = 5) for prostacycline (p < 0.05 versus adenosine and prostaglandin E₁). 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 E₁ and adenosine. At the highest concentration of 1 μM, the vasodilatory effect of adenosine was significantly less expressed, compared to that of prostaglandin E₁ (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 E₁. The rank order at the vasodilatory potency is prostacycline > prostaglandin E₁ > adenosine.