دورية أكاديمية
Differential Ca2+-dependence of transmitter release mediated by P/Q- and N-type calcium channels at neonatal rat neuromuscular junctions
| العنوان: | Differential Ca2+-dependence of transmitter release mediated by P/Q- and N-type calcium channels at neonatal rat neuromuscular junctions |
|---|---|
| المؤلفون: | Rosato-Siri, M.D., Piriz, J., Giugovaz Tropper, B.A., Uchitel, O.D. |
| المجموعة: | Biblioteca Digital FCEN-UBA (Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires) |
| مصطلحات موضوعية: | Actives sites, BAPTA-AM, EGTA-AM, Paired-pulse facilitation, calcium channel N type, calcium ion, omega agatoxin, omega conotoxin, 1,2 bis(2 aminophenoxy)ethane N,N,N',N' tetraacetic acid acetoxymethyl ester, 1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester, agents interacting with transmitter, hormone or drug receptors, calcium, calcium channel blocking agent, calcium channel P type, chelating agent, drug derivative, edetic acid, egtazic acid, omega agatoxin IVA, omega conotoxin GVIA, animal tissue, article, concentration (parameters), controlled study, extracellular space, facilitation, nerve ending, nerve stimulation, neuromuscular synapse |
| الوصف: | N- and P/Q-type voltage dependent calcium channels (VDCCs) mediate transmitter release at neonatal rat neuromuscular junction (NMJ). Thus the neonatal NMJ allows an examination of the coupling of different subtypes of VDCCs to the release process at a single synapse. We studied calcium dependence of transmitter release mediated by each channel by blocking with ω-conotoxin GVIA the N-type channel or with ω-agatoxin IVA the P/Q-type channel while changing the extracellular calcium concentration ([Ca2+]o). Transmitter release mediated by P/Q-type VDCCs showed steeper calcium dependence than N-type mediated release (average slope 3.6 ± 0.09 vs. 2.6 ± 0.03, respectively). Loading the nerve terminals with 10 μM BAPTA-AM in the extracellular solution reduced transmitter release and occluded the blocking effect of ω-conotoxin GVIA (blockade -2 ± 9%) without affecting the action of ω-agatoxin IVA (blockade 85 ± 4%). Both VDCC blockers were able to reduce the amount of facilitation produced by double-pulse stimulation. In these conditions facilitation was restored by increasing [Ca2+]o). The facilitation index (fi) was also reduced by loading nerve terminals with 10 μM BAPTA-AM (fi = 1.2 ± 0.1). The control fi was 2.5 ± 0.1. These results show that P/Q-type VDCCs were more efficiently coupled to neurotransmitter release than were N-type VDCCs at the neonatal neuromuscular junction. This difference could be accounted for by a differential location of these channels at the release site. In addition, our results indicate that space-time overlapping of calcium domains was required for facilitation. |
| نوع الوثيقة: | journal/newspaper |
| اللغة: | unknown |
| العلاقة: | http://hdl.handle.net/20.500.12110/paper_0953816X_v15_n12_p1874_RosatoSiriTest |
| الإتاحة: | https://doi.org/20.500.12110/paper_0953816X_v15_n12_p1874_RosatoSiriTest https://hdl.handle.net/20.500.12110/paper_0953816X_v15_n12_p1874_RosatoSiriTest |
| حقوق: | info:eu-repo/semantics/openAccess ; http://creativecommons.org/licenses/by/2.5/arTest |
| رقم الانضمام: | edsbas.6ECBAB56 |
| قاعدة البيانات: | BASE |
| الوصف غير متاح. |