Cardiovascular effects of some 2-substituted triazolo[1,5-a]pyrimidin-7(4H)one-6-carboxylic acid ethyl esters.

The cardiovascular effects of a series of 2-substituted- 1,2,4-triazolo[1,5-a]-pyrimidine derivatives (compounds 1-6) were examined in anaesthetized rats. Of these compounds only compounds 3 and 4 in dose of (15-60 mumole/Kg) induced dose-dependent decreases in the arterial blood pressure and heart rate. The induced cardiovascular changes were not antagonised by histaminergic, cholinergic, serotoninergic receptor blockers, prostaglandin synthesis inhibitors or Cacl2. Treatment of the animals with the compounds (20-30 mumole/Kg) competitively antagonised noradrenaline-induced increase in the arterial blood pressure and significantly antagonised isoprenaline-induced tachycardia but not the induced hypotension. The compounds seemed to possess both alpha 1- and, beta 1-adrenoceptor blocking activities.