The beta-adrenergic responses in isolated splenic capsule area of several species of animals.

In isolated splenic capsules of mouse, rat, guinea pig, rabbit, cat and dog, either a single or a cumulative dose of l- and dl-isoproterenol at a concentration higher than l0(-9) M, induced a relaxation which was inhibited or blocked with pretreatment of 10(-5) M propranolol. At a concentration of 5 x 10(-6) M to 10(-5) M 1- 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. Thus, it was confirmed that both alpha- and beta-receptors exist in the splenic capsule area of these different species.