Nicotinic Receptors on Vagal Nerve Terminals in the Atrium
The presence of presynaptic receptors on cardiac sympathetic nerve terminals, which control the release of norepinephrine, has been described by various investigators (see Starke, 1977; Westfall, 1977; Lokhandwala, 1979). In contrast there has been no report of presynaptic receptors at the vagal (parasympathetic) nerve terminals in the heart. This paper reports that the vagal postganglionic nerve terminals in the atrium of the guinea-pig are endowed with nicotinic receptors and that activation of these receptors results in the facilitation of acetylcholine (ACh) release from the nerve terminals (Odawara and Nishi, 1980). It will be also reported that the terminal nicotinic receptors are quite similar in pharmacological characteristics to the extrasynaptic nicotinic receptors on the postganglionic neuron soma.
KeywordsNerve Terminal Nicotinic Receptor Atrial Contraction Spontaneous Contraction Presynaptic Receptor
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