On the mechanism of the depressor reaction upon afferent vagal stimulation in cats. II. Role of the beta-adrenergic structures for the development of the depressor reaction.

Electrical stimulation of the central section of the cervical vagus in cats with bilateral vagotomy results in lowering of the arterial blood pressure. A study is made of the effect of some beta-adrenotropic drugs on the depressor reaction. Propranolol (3 mg/kg i.v.) causes considerable blocking of the depressor reaction in all experiments. On the other hand, Isoprenaline ( a. 10 mug/kh/min) results in a considerable increase of this reaction. The administration of Propranolol (3 mg/kg) and Phentolamine (2 mg/kg) causes almost complete blocking of the reaction. A conclusion is made on the basis of these data that both alpha- and beta-adrenergic structures take part in the realization and development of the depressor reaction upon afferent vagal stimulation.