Quantitative analysis on isolated organs of the autonomic blocking properties of indoramin hydrochloride (Wy 21901)

1. Indoramin is a competitive alpha-adrenoceptor blocking agent on the guinea-pig isolated vas deferens and aortic strip; the pA(2) value on the aorta is 7.4.2. Indoramin is devoid of beta-adrenoceptor blocking activity on the guinea-pig isolated trachea (10(-4)M) and the Langendorff preparation of the rabbit heart (10(-6)M). It also has no adrenergic neurone blocking action on the Finkleman preparation of the rabbit small intestine (10(-5)M).3. On the Langendorff preparation of the rabbit isolated heart, indoramin (above 10(-6)M) has cardio-inhibitory properties similar to those of propranolol.4. On the guinea-pig isolated ileum (10(-5)M) and trachea (10(-6)M), indoramin is devoid of anticholinergic activity, but has a potent antihistamine action which satisfies the criteria for competitive antagonism; the pA(2) value for this antagonism on the ileum is 8.2.5. Indoramin antagonizes 5-hydroxytryptamine on the rat isolated fundus and ileum; the pA(2) value for the antagonism on the ileum is 6.0.