THE EFFECTS OF PHARMACOLOGIC AGENTS ON THE PULMO-NARY CIRCULATION IN THE DOG. STUDIES ON EPINEPHRINE, NOR-EPINEPHRINE, 5-HYDROXYTRYPTAMINE, ACETYLCHOLINE, HISTAMINE AND AMINOPHYLLINE 1

Abstract

A preparation was used which permitted the differentiation of true pulmonary vasomotor changes from secondary mechanical changes in the lung vessels. Unilateral pharmacologically induced pulmonary vasomotion was studied with a number of drugs. Epinephrine, norepinephrine and 5-hydroxytryptamine produced consistent pulmonary vasoconstriction. Of the drugs studied, 5-hydroxytryptamine had the most marked pulmonary vasomotor effect. Acetylcholine and histamine increased transpulmonary pressure. When this effect was prevented from occurring, inconsistent pulmonary vasomotor effects of small magnitude were found. Aminophylline produced pulmonary vasodilation in some animals while it had no effect in others. The prerequisites for the assessment of active pulmonary vasomotor changes are discussed.