Long-term administration of the adenosine receptor antagonist, 1,3-dipropyl-8-sulfophenylxanthine (DPSPX), causes arterial hypertension and cardiovascular hypertrophic and hyperplastic changes (Matias, Albino-Teixeira, Polónia & Azevedo, 1991). As somatostatin is a repressor of cell growth, and adenosine is a potent inducer of the somatostatin gene, we investigated the putative involvement of somatostatin in the cardiovascular effects of DPSPX. 2. DPSPX (90 micrograms kg-1 h-1, i.p.) or saline and the somatostatin analogue, octreotide (75 micrograms kg-1 day-1, s.c.), or saline were infused through Alzet minipumps to Wistar rats. Blood pressure was measured with the tail-cuff technique. Seven days after implantation of the minipumps the rats were killed and the tissues prepared for microscopy. 3. DPSPX induced arterial hypertension and cardiovascular hypertrophic and hyperplastic changes as previously described (Matias et al., 1991). Treatment of the rats with octreotide alone had no effect either on blood pressure or in blood vessel morphology. However, octreotide prevented both the hypertensive and the cardiovascular morphologic effects of DPSPX. 4. The results are compatible with the involvement of somatostatin in the long-term cardiovascular effects of adenosine.
