EFFECT OF ASPIRIN TREATMENT ON THE HYPOTENSIVE EFFECT OF CLONIDINE IN RATS

  • 1 January 1983
    • journal article
    • research article
    • Vol. 264  (2) , 298-304
Abstract
Rats were pretreated with aspirin (5 mg/kg i.p. 5 days) or saline, anesthetized with pentobarbitone, and blood pressure recorded from the carotid artery. Clonidine (30 .mu.g/kg) was injected i.v. via a cannula inserted into the femoral vein. Aspirin pretreatment significantly reduced the hypotensive effect of clonidine. Spleen, heart brain, kidneys and lung were removed from the animals 60 min after clonidine administration. Prostaglandin [PG] biosynthesis from endogenous substrate was determined by homogenizing tissues (1:4 wt/vol in either Tris buffer (pH 7.4) or in 1M formic acid: ethanol (1:Vol/vol). PG were extracted into ethyl acetate and bioassayed on the rat stomach strip. Clonidine administration significantly increased the PG formation in heart, brain and kidney. Animals pretreated with aspirin showed a reduction in the clonidine-induced increase in PG synthesis in heart, brain and spleen. The hypotensive effect of clonidine in anesthetized rats may in part be secondary to stimulation of central PG biosynthesis.