Abstract
The perfusion of the sinus node artery in 9 dogs in situ was performed. The selective injection of aminophylline into the sinus node artery induced a positive chrono-tropic response. The positive chronotropic response to aminophylline was suppressed not only by propranolol but also by tetrodotoxin. It is suggested that the positive chronotropic action of aminophylline is partially due to catecholamine release from adrenergic nerve terminals by excitation of local nerve fibers.
