THE β-ADRENERGIC RESPONSES IN ISOLATED SPLENIC CAPSULE AREA OF SEVERAL SPECIES OF ANIMALS

Abstract

In isolated splenic capsules of mouse, rat, guinea pig, rabbit, cat and dog, either a single or a cumulative dose of 1-isoproterenol and d1-isoproterenol at a concentration higher than 10-9 M, induced a relaxation which was inhibited or blocked with pretreatment of 10-5 M propranolol. At a concentration of 5 .times. 10-6 M to 10-5 M l-isoproterenol and dl-isoproterenol, an inverse contraction was induced, and such response was prevented or reversed to one of relaxation in the presence of 10-5 M phentolamine. Application of 10-5 M epinephrine produced a strong contraction and such was reversed to one of relaxation after addition of 10-4 M phentolamine. This relaxation was reduced or blocked with pretreatment of 10-5 M propranolol. Both .alpha. and .beta. receptors may exist in the splenic capsule area of these different species.