Effect of an original piperazine derivative of tetraline on the adrenergically mediated metabolic responses in cats and rats.

One piperazine derivative of tetraline (with code P11), possessing hypotensive and anti-hypertensive activity, is studied. Its alpha- and beta-adrenoceptor blocking properties are characterized by using indicators of adrenergically mediated metabolic responses in cats and rats. The parameters studied are: glucose and lactate in the blood, free fatty acids in the plasma and the activity of phosphorylase "a" in rat myocardium. The alpha- and beta-adrenergic properties of P11 are characterized by using adrenergic and dopaminergic agonists and antagonists (adrenaline, isoproterenol, phenylephrine, propranolol, phentolamine, apomorphine and pimozide) in the different experimental setups. Compound P11 studied inhibits the effect of phenylephrine on the glucose level in the blood of rats in a definite dose interval (1-4 mg/kg) which suggests that it possesses alpha-adrenoblocking properties. P11 decreases slightly the effects of isoproterenol or does not change these effects on the levels of glucose, lactate and free fatty acids in cats. There are no changes in the effect of adrenaline on the glucose content in rat blood and the isoproterenol-activated phosphorylase in rat myocardium is not inhibited. This gives grounds to assume that P11 possesses slight beta-adrenoblocking properties. From the analysis of the proper hyperglycaemizing action of P11 in rats in the 1-8 mg/kg dose range it may be assumed that dopamine-agonistic mechanisms are involved.