title: Functional expression of T-type Ca2+ channels in spinal motoneurons of the adult turtle.
abstract: Voltage-gated Ca2+ (CaV) channels are transmembrane proteins comprising three subfamilies named CaV1, CaV2 and CaV3. The CaV3 channel subfamily groups the low-voltage activated Ca2+ channels (LVA or T-type) a significant role in regulating neuronal excitability. CaV3 channel activity may lead to the generation of complex patterns of action potential firing such as the postinhibitory rebound (PIR). In the adult spinal cord, these channels have been found in dorsal horn interneurons where they control physiological events near the resting potential and participate in determining excitability. In motoneurons, CaV3 channels have been found during development, but their functional expression has not yet been reported in adult animals. Here, we show evidence for the presence of CaV3 channel-mediated PIR in motoneurons of the adult turtle spinal cord. Our results indicate that Ni2+ and NNC55-0396, two antagonists of CaV3 channel activity, inhibited PIR in the adult turtle spinal cord. Molecular biology and biochemical assays revealed the expression of the CaV3.1 channel isotype and its localization in motoneurons. Together, these results provide evidence for the expression of CaV3.1 channels in the spinal cord of adult animals and show also that these channels may contribute to determine the excitability of motoneurons.
authors.affiliation: Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies of the National Polytechnic Institute (Cinvestav-IPN), Mexico City, Mexico.
authors.forename: Martha
authors.initials: M
authors.lastname: Canto-Bustos
authors.affiliation: Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies of the National Polytechnic Institute (Cinvestav-IPN), Mexico City, Mexico.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Loeza-Alcocer
authors.affiliation: Department of Molecular Biology and Histocompatibility, "Dr. Manuel Gea González" General Hospital, Mexico City, Mexico.
authors.forename: Ricardo
authors.initials: R
authors.lastname: González-Ramírez
authors.affiliation: Department of Cell Biology, Cinvestav-IPN, Mexico City, Mexico.
authors.forename: María A
authors.initials: MA
authors.lastname: Gandini
authors.affiliation: Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies of the National Polytechnic Institute (Cinvestav-IPN), Mexico City, Mexico.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Delgado-Lezama
authors.affiliation: Department of Cell Biology, Cinvestav-IPN, Mexico City, Mexico.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Felix
mesh_terms: D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020747:Calcium Channels, T-Type / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D008564:Membrane Potentials; D009046:Motor Neurons / Q000187:drug effects / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology* / Q000378:metabolism*; D014426:Turtles
chemical_list: D002121:Calcium Channel Blockers; D020747:Calcium Channels, T-Type