抄録
The effects of tremorine and oxotremorine were investigated in seven vagotomized dogs, using direct perfusion technique of the S-A node under constant perfusion pressure of 100mm Hg. 1) Tremorine (30 μg to 1mg) and oxotremorine (0.003 to 0.03 μg) injected into the sinus node artery induced a negative chronotropic effect. This negative chronotropic effect was blocked by atropine, but was not influenced by tetrodotoxin and propranolol. 2) Higher doses of oxotremorine produced long-lasting atrial fibrillation. At doses larger than 0.3 μg, oxotremorine induced atrial fibrillation in all animals. The induction and maintenance of atrial fibrillation were blocked by atropine. The induction was also prevented by a large amount of tetrodotoxin and propranolol in some animals. A large dose of propranolol occasionally blocked the maintenance of atrial fibrillation.
