AJP - Regulatory, Integrative and Comparative Physiology, Vol 259, Issue 2 288-R293, Copyright © 1990 by American Physiological Society
Presynaptic modulation of ganglionic ACh release by muscarinic and nicotinic receptors
Z. Dujic, D. L. Roerig, H. K. Schedewie, J. P. Kampine and Z. J. Bosnjak
Department of Anesthesiology, Medical College of Wisconsin, Milwaukee.
The present experiments were undertaken to investigate the effects of
atropine and d-tubocurarine on acetylcholine (ACh) release and ganglionic
synaptic transmission in the isolated cat stellate ganglion. Ganglionic
release of picomole amounts of ACh was measured by radioenzymatic assay,
and ganglionic transmission was estimated on the basis of the compound
action potential recorded from the postganglionic stellate cardiac nerve.
Atropine (5 microM) produced a significant increase in both spontaneous and
evoked ACh release from the ganglion while depressing synaptic
transmission. d-Tubocurarine (20 microM) also caused a significant, though
smaller, increase in spontaneous release of ACh but had little effect on
evoked release of ACh. These results suggest that ACh release and synaptic
transmission in the cat stellate ganglion are subject to cholinergic
feedback regulation, which appears to be mediated predominantly via
muscarinic presynaptic receptors.
