Instantaneous cardiac acceleration in the cat elicited by peripheral nerve stimu- lation

peripheral nerve stimulation on heart rate was studied in de-cerebrate cats. Stimulus trains (100 Hz) of l-s duration were given to the tibia1 nerve or to muscle nerves with an intensity yielding a maximal force of isometric contraction of the triceps surae muscle. The first detectable sign and the maximum of cardiac cycle length shortening were found at 0.5-0.6 and 2.1 & 0.4 (SD) s, respectively, after the onset of stimulation. A positive correlation exists between the basic cycle length (i.e., before nerve stimulation) and the stimulation-induced short-ening of cycle length. The average maximum shortening was found to be 6.7 % of.basic cycle length. Atropine (0.05-0.1 mg/ kg) or bilateral vagotomy suppresses the heart rate response almost completely, whereas the administration of propranolol (2 mg/kg) leaves the response intact. When the nerve is cut proximal to the site of stimulation, the response disappears