Differential vasodilatory action of 2-octynyladenosine (YT-146), an adenosine A2 receptor agonist, in the isolated rat femoral artery and vein.

The vasodilatory action of 2-octynyladenosine (YT-146), an adenosine A2 receptor agonist, was investigated in the isolated rat femoral artery and vein. Exposure to YT-146 resulted in preferential vasodilatation; the vein was completely dilated at YT-146 concentrations as low as 10(-7) M; in contrast, a concentration of YT-146 greater than 10(-4) M was necessary to induce complete relaxation in the femoral artery. 2-[p-(2-Carboxyethyl)-phenethylamine]-5'-N-ethylcarboxamidoadenosine (CGS 21680) also evoked stronger dilation in the vein than in the artery. The vasodilatory action of N6-cyclopentyladenosine (CPA) was much weaker in the vein than that of YT-146. YT-146-induced vasodilation in the artery was antagonized by neither 10(-7) M 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) nor 3 x 10(-6) M (E)-8-(3,4-dimethoxystylyl)-1,3-dipropyl-7-methylxanthine (KF17837), while the vasodilation in the vein was only antagonized by KF17837, suggesting that the vasodilation may involve adenosine A2 receptor activation in the vein. However, the present study did not provide evidence of a link between adenosine agonist-induced vasodilation and adenosine A2 receptor activation in the artery. The addition of 10(-4) M N omega-nitro-L-arginine partially reversed YT-146-induced vasodilation in the artery, but not in the vein. The reversal of YT-146-induced vasodilation by N omega-nitro-L-arginine in the artery was attenuated by the addition of 10(-3) M L-arginine. Removal of the endothelium decreased YT-146-induced vasodilation in the artery, but not in the vein.(ABSTRACT TRUNCATED AT 250 WORDS)