Nitric oxide mediates the blood flow response to intravenous adenosine in the rabbit

The objective of this study was to determine if nitric oxide mediates the effects of exogenously administered adenosine on peripheral blood flow. An intravenous infusion of adenosine (1.0 mumol/kg/min) into male New Zealand white rabbits caused an increase in blood flow, measured using radiolabeled microspheres, throughout the gastrointestinal tract, as well as in the heart and kidneys. Prior administration of nitro-L-arginine methyl ester (L-NAME) 10 mg/kg i.v. completely blocked the hyperemic effect of adenosine on all organs studied. Administration of L-arginine (300 mg/kg bolus and 50 mg/kg/min infusion) together with L-NAME restored the hyperemic effect of adenosine. This phenomenon was specified to the L-arginine/nitric oxide pathway in that a similar pressor response induced by phenylephrine (1.5 micrograms/kg/min) did not block the effects of adenosine. We conclude that the peripheral vasodilator response to intravenously administered adenosine in the rabbit is mediated by nitric oxide.