Intrinsic heart rate in the dog determined by pharmacologic denervation

19 dogs undergoing 76 experiments (conscious n=16, neuroleptanesthesia n=54, pentobarbital sodium n=6)

Pharmacologic autonomic blockade (phenoxybenzamine 2 mg/kg, propranolol 2 mg/kg followed by 2 mg/kg/h, atropine 0.5 mg/kg followed by 0.5 mg/kg/h, and hexamethonium 20 mg/kg followed by 10 mg/kg/h or bilateral cervical vagotomy)

Intrinsic heart ratesurrogate