AUTONOMIC AND CARDIOVASCULAR EFFECTS OF NEUROMUSCULAR BLOCKADE ANTAGONISM IN THE DOG

Autonomic and cardiovascular changes were studied when neuromuscular blockade was antagonized in 96 dogs with one of eight anticholinesterase-antimuscarinic drug combinations. Neostigmine (50 or 100-mu-g/kg) was administered before or after atropine (40-mu-g/kg) or glycopyrrolate (10-mu-g/kg). The high dose of neostigmine (100-mu-g/kg) caused bradyarrhythmias, salivation, and signs of bronchosecretion when used with either antimuscarinic agent and irrespective of the administration sequence. The heart rate increased, but not significantly, when atropine was injected before either dose of neostigmine. This did not occur when this administration sequence was reversed. Arrhythmias and cardiovascular and autonomic changes did not occur when glycopyrrolate was injected before or after neostigmine at 50-mu-g/kg.