© 1968 American Heart Association, Inc.
Abnormal Response of the Pulmonary Artery of the Rabbit after High Frequency Sympathetic Nerve Stimulation
1 Department of Pharmacology, University of California Los Angeles School of Medicine, Los Angeles, California 90024
When the sympathetic nerve supply (right recurrent cardiac nerve) to a ring of the pulmonary artery of the rabbit is stimulated repetitively in vitro at frequencies of 10/second or more, the following changes occur which are not seen after stimulation at lower frequencies. (1) The minimum number of pulses in a train needed to cause a just-detectable contractile response is reduced from a mean of 7 to unity; the higher the frequency of repetitive stimulation the fewer the number of repetitive pulses needed to effect this change. (2) The basal tone of the blood vessel exhibits fairly rapid, small, spontaneous fluctuations. (3) The resting or basal tone of the vessel slowly increases for 1/2 to 2 hours. It is speculated that changes 1 and 2 may be the result of an irreversible change in transmitter storage or release mechanisms.
Key Words: spontaneous changes in vascular tone • adrenergic transmitter • arterial innervation • neurogenic tone •
adrenergic blocking agents • increased vascular tone • facilitated transmitter release
Accepted on December 10, 1967