Adenosine has been shown recently to be the main factor responsible for the trophic effects of sympathetic innervation. As sympathetic denervation causes hypertrophic and hyperplastic changes reminiscent of those occurring in blood vessels of spontaneously hypertensive rats, we decided to study the effect of a continuous blockade of adenosine receptors on both blood vessel structure and blood pressure. A continuous infusion of 1,3-dipropyl-8-sulfophenylxanthine (DPSPX; 30 micrograms/kg per h for 7 days) to Wistar rats caused hyperplastic changes in peritoneal fibroblasts and mesenteric arterioles, hypertrophic changes in the smooth muscle of the tail artery and significant increase in the size of left ventricle myocardial cell nuclei. Both diastolic and systolic blood pressure increased significantly above control values. The results confirmed the trophic effects of adenosine and showed that chronic blockade of adenosine receptors causes arterial hypertension.