Adenosine alters the vascular effects of a diacylglycerol analogue and polymyxin B

Endothelium-denuded rat aorta rings were used to study the possible relationship between protein kinase C and the mechanism of adenosine-induced smooth muscle relaxation. Adenosine (5 × 10⁻⁴M) partially relaxed the aortic rings contracted by either a depolarising amount of KCl (4 × 10⁻² M) or activation of protein kinase C with l-oleoyl-2- acetyl-sn-glycerol (10⁻⁶ M). The same amount of adenosine blocked the further relaxation obtained in the presence of polymyxin B (5 × 10⁻⁵ M), a protein kinase C blocking agent. These results suggest a possible interaction in vascular smooth muscle between adenosine and protein kinase C.