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.
KeywordsPermeability Depression Nicotine Iodide Histamine
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- Bhagat, B., Robinson, I. M., and West, W. L., 1967, Mechanism of sympathomimetic responses of isolated guinea-pig atria to nicotine and dimethylphenylpiperazinium iodide, Br. J. Pharmacol., 30: 470.Google Scholar
- Giotti, A., 1954, Interaction of nicotine and eserine, ephedrine, atropine, hexamethonium and adrenaline in isolated guinea-pig auricles, Br. J. Pharmacol., 9: 15.Google Scholar
- Khan, M., Mantegazza, P., and Piccinini, F., 1965, Effect of low temperatures on the responses of guinea-pig isolated atria to nicotine and to sympathetic and parasympathetic stimulation, Br. J. Pharmacol., 25: 119.Google Scholar
- Leaders, F. E., and Long, J. P., 1962, Mechanism of the positive chronotropic response to nicotine, Pharmacol. Exp. Ther., 137: 206.Google Scholar
- Odawara, K., and Nishi, S., 1980, The nicotinic receptors at the vagal efferent nerve terminals in the atrium, Proc. Internat. Union Physiol. Sci., 14: 618.Google Scholar
- Takeuchi, N., 1963, Effects of calcium on the conductance change of the end-plate membrane during the action of transmitter, J. Physiol. (Lond.), 167: 141.Google Scholar
- Takeuchi, A., and Takeuchi, N., 1960, On the permeability of end-plate membrane during the action of the transmitter, J. Physiol. (Lond.), 154: 52.Google Scholar