Facilitation, augmentation, and potentiation of synaptic transmission at the superior cervical ganglion of the rabbit

J. E. Zengel, K. L. Magleby, J. P. Horn, D. A. McAfee, P. J. Yarowsky

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62 Scopus citations

Abstract

The effect of repetitive stimulation on synaptic transmission was studied in the isolated superior cervical ganglion of the rabbit under conditions of reduced quantal content. Excitatory postsynaptic potentials (EPSP) were recorded with the sucrose gap technique to obtain estimates of transmitter release. Four components of increased transmitter release, with time constants of decay similar to those observed at the frog neuromuscular junction at 20°C, were found in the ganglion at 34°C: a first component of facilitation, which decayed with a time constant of 59 ± 14 ms (mean ± SD); a second component of facilitation, which decayed with a time constant of 388 ± 97 ms; augmentation, which decayed with a time constant of 7.2 ± 1 s; and potentiation, which decayed with a time constant of 88 ± 25 s. The addition of 0.1-0.2 mM Ba 2+ to the Locke solution increased the magnitude but not the time constant of decay of augmentation. Ba 2+ had little effect on potentiation. The addition of 0.2-0.8 mM Sr 2+ to the Locke solution appeared to increase the magnitude of the second component of facilitation. Sr 2+ had little effect on augmentation or potentiation. These selective effects of Ba 2+ and Sr 2+ on the components of increased transmitter release in the rabbit ganglion are similar to the effects of these ions at the frog neuromuscular junction. Although the effects of Ba 2+ and Sr 2+ are similar in the two preparations, the magnitudes of augmentation and the second component of facilitation after a single impulse were about 6-10 times greater in the rabbit ganglion than at the frog neuromuscular junction. These results suggest that the underlying mechanisms in the nerve terminal that give rise to the components of increased transmitter release in the rabbit ganglion and frog neuromuscular junction are similar but not identical.

Original languageEnglish (US)
Pages (from-to)213-231
Number of pages19
JournalJournal of General Physiology
Volume76
Issue number2
DOIs
StatePublished - Aug 1 1980

ASJC Scopus subject areas

  • Physiology

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