Acetylcholine Release from Rat Diaphragm: A Search for Release Regulatory Mechanisms
During the last five years there have been a number of reports concerned with possible muscarinic mechanisms at the motor nerve terminals of the phrenic nerve. Both positive and negative muscarinic feedback autoregulation of acetylcholine (ACh) release has been suggested, as well as an absence of any regulatory muscarinic receptor. The designs of the previously performed experiments differ from each other and from ours mainly in the technique used for ACh analysis. There are also differences in the use of anticholinesterases. It is possible that these differences in approach may have led to the divergent results. We decided to reinvestigate the possible involvement of a presynaptic muscarinic autoreceptor in ACh release from motoneurons. For this purpose a chemiluminescence technique for the quantitation of ACh released from mammalian neuromuscular preparations was developed. Nerve stimulation was accomplished either by 50 mM KCl or by electrical stimulation of the phrenic nerve.
KeywordsPhrenic Nerve Acetylcholine Release Motor Nerve Terminal Nicotinic Antagonist Chemiluminescence Technique
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