Hemodynamic Effects of Adenosine Agonists in the Conscious Spontaneously Hypertensive Rat

The present studies examined the underlying hemodynamic mechanisms contributing to the reduction in blood pressure observed in conscious spontaneously hypertensive rats after systemic administration of adenosine agonists. The effects pro-duced by i.v. and i.a. injections of 2-phenylaminoadenosine [CV-1 808, adenosine (A2) selective agonist], 5’-N-ethylcarboxamide adenosine (NECA, nonselective agonist), 2-chloroadenosine (2-CADO, A1 selective agonist) and cyclopentyladenosine (CPA, A1 selective agonist) were evaluated and compared to those of hydralazine. All agents produced hypotensive effects after bolus i.v. injection. Although CPA, NECA and 2-CADO elicited dose-dependent bradycardia, CV-1 808 and hydralazine increased heart rate. These effects, with the exception of the hydralazine-evoked responses, were attenuated by prior treatment with 8-(p-sulfophenyl)theophylline (2 mg/kg/mm), whereas both CV