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Cardiovascular effects of two xanthines and the relation to adenosine antagonism
Author(s) -
Smits Paul,
Schouten Jan,
Thien Theo
Publication year - 1989
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1038/clpt.1989.79
Subject(s) - antagonism , adenosine , pharmacology , medicine , cardiology , receptor
We hypothesize that the hemodynamic effects of xanthine derivatives depend on their ability to antagonize the vasodilating effects of endogenous adenosine. In a randomized, double‐blind, and placebo‐controlled study of 10 normotensive volunteers caffeine, a xanthine with in vitro adenosine antagonistic properties, increased mean arterial pressure by 5.6 ± 0.9 mm Hg and lowered heart rate by 5.3 ±1.1 beats/min. After administration of enprofylline, a xanthine without adenosine antagonism, forearm vascular resistance decreased by 5.6 ± 3.4 IU, heart rate increased by 10.6 ± 2.6 beats/min, and plasma adrenaline, plasma noradrenaline, and renin activity increased by 178 ± 86%, 14 ± 8%, and 36 ± 13%, respectively. Adenosine infusion alone induced a dose‐related increase in pulse pressure and heart rate, and it increased plasma adrenaline and noradrenaline by 186 ± 77% and 132 ± 55%, respectively. This response to adenosine was reduced by pretreatment with caffeine but not enprofylline. Thus opposite circulatory responses to caffeine and enprofylline occurred, with signs of vasoconstriction and vasodilation, respectively. In addition, caffeine, but not enprofylline, reduced the cardiovascular response to exogenous adenosine. Clinical Pharmacology and Therapeutics (1989) 45 , 593–599; doi: 10.1038/clpt.1989.79