K. Sakai et al., ROLE FOR ADENOSINE A(1) AND A(2) RECEPTORS IN FEMORAL VASODILATATION INDUCED BY INTRAARTERIAL ADENOSINE IN RABBITS, European journal of pharmacology, 353(2-3), 1998, pp. 257-264
The vasodilator effects of adenosine injected into the femoral artery
(i.a.) of rabbits were analyzed. Single bolus i.a. doses of adenosine
(0.3-10 mu g) and 5'-(N-cyclopropyl)-carboxamidoadenosine (CPCA)(0.03-
1 mu g), an adenosine A(2)-receptor agonist, produced dose-dependent i
ncreases in femoral blood flow and decreases in resistance, almost wit
hout affecting blood pressure, heart rate, left ventricular (LV) press
ure, and LVdP/dt max, even though CPCA elicited slight decreases in ar
terial blood pressure and LV pressure. On the other hand, bolus i.a. i
njections of N-6-cyclopentyladenosine (CPA) (1-30 mu g), an adenosine
A(1) receptor agonist, caused a relatively weak increase in blood flow
, but markedly affected cardiac parameters, especially heart rate and
LVdP/dt max. I.v. treatment with 3,7-dimethyl-1-propargylxanthine (DMP
X)(2 mg kg(-1)), an antagonist of adenosine A(2) receptors, or 8-pheny
ltheophylline (1 mg kg(-1)), an antagonist of adenosine A(2) receptors
, significantly attenuated the vasodilator response to adenosine, but
not that to acetylcholine. Decreases in blood pressure, heart rate, LV
pressure, LVdP/dt max and femoral vascular resistance, and increases
in the blood flow elicited by CPA were not significantly modified by t
he DMPX treatment, but when this was combined with 8-phenyltheophyllin
e, the responses to CPA were completely abolished. The present results
indicate that the adenosine-induced femoral vasodilatation in rabbits
may be mediated throughout activation of both adenosine A(1) and A(2)
receptors. (C) 1998 Elsevier Science B.V. All rights reserved.