THE BLOCKING ACTION OF PRONETHALOL ON THE CONTRACTION OF ISOLATED SPLEEN STRIPS PRODUCED BY ADRENALINE, ACETYLCHOLINE OR ISOPROTERENOL

Abstract

The effects of an antagonist (pronethalol) on the contraction of spleen strips produced by agonists (epinephrine acetylcholine and isoproterenol) were studied in the preparations prepared from kids and rabbits. The same study was done using adrenaline as an agonist also in rabbits. High concentrations of pronethalol (about 10-5 g/ml or more) inhibited the responses of the spleen strips to each of the agonists in all the experiment done. The augmentation of the responses of spleen strips to each of the agonists occurred in the presence of low concentrations of pronethalol (below 10-6 g/ml) in kids. A significant augmentation of the responses to the 3 agonists was not observed with a previous addition of low concentrations of pronethalol, in the experiment with cats. In rabbits, the augmentation of the response to adrenaline with an addition of low concentrations of pronethalol, was not observed either. The inhibitory effects of high concentrations of pronethalol on the contraction of spleen strips produced by epinephrine, acetylcholine or isoproterenol, are not due to the specific action of pronethalol on the beta-adrenergic receptors.