Adenosine inhibits leukocyte-induced vasoconstriction.

Polymorphonuclear leukocytes (PMNs) can induce endothelium-dependent constriction of vascular rings. Because adenosine inhibits the function of PMNs, we examined the effects of adenosine on the PMN-induced coronary vasoconstriction. We measured changes in the isometric tension of isolated rings of canine coronary arteries suspended in an organ chamber filled with Krebs-Henseleit solution after the addition of autologous PMNs. N-formyl-L-methionyl-leucyl-phenylalanine (FMLP)-stimulated PMNs increased the tension of the coronary artery with the endothelium in a concentration-dependent manner. Treatment of FMLP-stimulated PMNs with adenosine inhibited both the adhesion of PMNs to the endothelium and the PMN-induced vasoconstriction. Stimulation of PMNs with CGS-21680C, but not with cyclohexyladenosine, inhibited both the adhesion of PMNs to the endothelium and the PMN-induced vasoconstriction. However, treatment of coronary arteries with adenosine had no effect on the adherence of PMNs to the endothelium and the PMN-induced constriction. These results suggest that stimulation of adenosine A2a receptors on PMNs may inhibit the PMN-induced vasoconstriction by inhibiting the adhesion of PMNs to the endothelium.