Embryonic rat motoneurons express a functional P-type voltage-dependent calcium channel |
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| Authors: | Bruno Hivert Sylvie Bouhanna Sylvie Diochot William Camu Govindan Dayanithi Christopher E Henderson Jean Valmier |
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| Institution: | 1. INSERM U.249, Institut de Biologie, Blvd Henri IV, 34060 Montpellier, France;2. INSERM U.298, CHRU, 49033 Angers, France;3. URA 1197 du CNRS, Université Montpellier II, 34095 Montpellier, Cédex 5, France;4. INSERM U382, 907 Luminy, 13288, Marseille, Cédex 8, France;1. Instituto de Biofísica Carlos Chagas Filho, Laboratório de Neuroquímica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil;2. Núcleo Multidisciplinar de Pesquisa em Biologia (Numpex-Bio), Campus de Duque de Caxias Geraldo Guerra Cidade, Universidade Federal do Rio de Janeiro, Duque de Caxias, RJ 25255-030, Brazil;1. Molecular and Cellular Biology Program, Oregon State University, Corvallis, OR 97331, USA;2. Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA;3. Linus Pauling Institute, Oregon State University, Corvallis, OR 97331, USA;1. Department of Physiology, University of Alberta, Edmonton, Canada;2. Department of Surgery, University of Alberta, Edmonton, Canada;3. Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada;1. The Jackson Laboratory, Bar Harbor, ME 04609, USA;2. The Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME 04469, USA;3. Center for Gene Therapy, The Research Institute at Nationwide Children’s Hospital, Columbus, OH, USA;4. Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, USA;1. Center for Basic Medical Research, Medical School of Nantong University, Nantong, Jiangsu Province, 226001, China;2. Department of Anesthesiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, 226001, China;3. Key Laboratory of Neuroregeneration of Jiangsu and the Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, 226001, China;4. Department of Hand Surgery, China-Japan Union Hospital of Jilin University, Changchun, Jilin Province, 130033, China;5. Medical School of Nantong University, Nantong, Jiangsu Province, 226001, China |
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| Abstract: | Only L- and N-type high voltage-activated calcium currents (HVA ICa) have been demonstrated in identified embryonic spinal motoneurons. However, pharmacological experiments suggest that other HVA ICa, including P-type, govern neurotransmitter release at the adult neuromuscular junction. We sought to analyse if embryonic motoneurons express these other ICa, using the whole-cell voltage-clamp method on motoneurons purified by a new metrizamide-panning technique from E15 rat embryos. In addition to L-type dihydropyridine-sensitive and N-type ω-GVIA-sensitive currents, motoneurons express two other HVA ICa. One has properties related to the P-type channel currents described in Purkinje cells: it is inhibited by the peptide ω-agatoxin-IVA with a maximal effect at 100–200 nM. The inhibited current has a characteristic sustained component during depolarizing test pulses. Furthermore, 50–100 nM concentration of ω-agatoxin-IVA reduce the increase in cytoplasmic calcium concentration observed after depolarization. The other HVA ICa is resistant to saturating concentrations of verapamil, ω-conotoxin GVIA and ω-agatoxin-IVA which block L, N and P-type HVAICa, respectively. These results suggest that it is now possible to dissect, using a simple method of purification, the properties of the ICa in embryonic mammalian motoneurons and to provide pharmacological evidence for multiple calcium channels which may be involved in regulation of their activity during development. |
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| Keywords: | calcium channels intracellular calcium concentration spinal motoneuron ω -Aga-IVA purification by immuno-panning |
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