Adrenaline reversal by CIBA 1002-Go

Abstract

In cats anaesthetized with pentobarbitone, CIBA 1002-Go (Go.1002) (0.5-1 mg/kg) produced reversal of pressor responses to adrenaline (AD) whereas responses to noradrenaline (NA) were not much affected. This difference between the two amines was not seen in rabbits. The depressor response to AD after Go.1002 was converted into a pressor response by propranolol (PR) (400 µg/kg i.v. in two divided doses). The hypertensive response after PR was greater in experiments on cats where Go.1002 had been given previously than in the controls. Go. 1002 also potentiated the effects of AD on rat uterus and this effect was blocked by PR. Cocaine (4.5 mg/kg i.v.), imipramine (4.5 mg/kg i.v.) and hexamethonium (7.5 mg/kg i.v.), given before or after Go.1002 blocked the depressor response of AD and converted it into a pressor response. From these results it is concluded that Go.1002 does not produce any significant a-adrenergic block and that the selective reversal of the response to AD is due to potentiation of the adrenergic vasodilation.