Antagonism of the cardiovascular effects of adenosine by caffeine or 8-(p-sulfophenyl)theophylline.

摘要: We compared the abilities of adenosine antagonists caffeine and 8-(p-sulfophenyl)theophylline (8-SPT) to block receptor-mediated hypotension bradycardia in anesthetized rats. Few quantitative data exist concerning amounts needed prevent cardiovascular effects physiologic plasma concentrations or site action (central peripheral) such blockade. Thus, dose-response curves were constructed for antagonism by 8-SPT caused infusing i.v. giving bolus injections analogs 2-chloroadenosine, R-phenylisopropyladenosine N-ethylcarboxamidoadenosine. also quantitated suppression ability potentiate nicotine-induced hypertension tachycardia. Caffeine (EC50 = 92 microM) 48 blocked produced elevating levels from 1.22 1.74 microM. Similar drug doses inhibit potentiation pressor chronotropic responses nicotine antagonize hypotensive negative As expected, neither nor demonstrated selectivity A1 (predominating at heart) vs. A2 blood vessels) receptor subtypes. Administration as much 50 mg/kg i.p. failed produce detectable brain drug, demonstrating its failure gain access central nervous system indicating that which antagonizes is peripheral.(ABSTRACT TRUNCATED AT 250 WORDS)