Acetylcholine-induced hyperpolarization in identified neurones of the African giant snail (Achatina fulica Férussac) |
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| Authors: | Y Furukawa M Kobayashi |
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| Affiliation: | 1. Nanotechnology and Advanced Materials Central Lab., Agriculture Research Center, Giza, Egypt;2. Regional Center for Food and Feed, Agriculture Research Center, Giza, Egypt;3. Biophysics Department, Faculty of Science, Cairo University, Giza, Egypt;4. British University in Egypt Misr Ismalia Road, Cairo, Egypt;2. Laboratory of Clinical Microbiology and Immunology, Faculty of Pharmacy, Federal University of Pará, Belém, Brazil;3. Department of Medical Sciences, Section of Pharmacology and National Institute of Neuroscience, University of Ferrara, Ferrara, Italy;4. Laboratory of Immunology, Department of Basic Health Sciences, Federal University of Health Sciences of Porto Alegre, Rua Sarmento Leite, Porto Alegre, Brazil;1. Institute of Agricultural Engineering, Fujian Academy of Agricultural Sciences, Fuzhou 350003, PR China;2. Fujian Key Laboratory of Agricultural Product (Food) Processing, Fuzhou 350003, PR China;3. Department of Food Science and Nutrition, School of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, PR China |
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| Abstract: | Three types of hyperpolarization in response to applied acetylcholine (ACh) were observed in 4 identified neurones (RP1, RP2, RP3 and RP4) in the right parietal ganglion of the African giant snail, Achatina fulica Férussac. In order to clarify the ionic mechanisms of these responses, the neurones were voltage-clamped using two microelectrodes and the reversal potential of the ACh-induced currents was measured under several external ionic environments. Experiments revealed the existence of two different ACh-induced currents (Cl- and K+). It was concluded that the 3 types of hyperpolarizing responses were due to the relative sizes of the two currents in a neurone. Effects of some cholinergic antagonists on these currents were studied. Benzoquinonium blocked both currents at nearly the same concentration. D-Tubocurarine, decamethonium and atropine blocked Cl- current but not K+ current. These drugs did not show any clear voltage-dependency on their blocking actions. Tetraethylammonium blocked the ACh-induced K+ current at a lower concentration than that needed to block the other K+ channels in molluscan neurones, but it had little effect on Cl- current. These results suggest that two currents may be mediated by different ACh receptors. |
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