The role of desensititation in decay time of miniature endplate currents in frogs Rana ridibunda and Rana temporaria

0142139 - FGU-C 20010193 RIV IE eng J - Journal Article
Giniatullin, R. A. - Talantova, M. V. - Vyskočil, František
The role of desensititation in decay time of miniature endplate currents in frogs Rana ridibunda and Rana temporaria.
Neuroscience Research. Roč. 39, č. 3 (2001), s. 287-292. ISSN 0168-0102. E-ISSN 1872-8111
R&D Projects: GA AV ČR IAA7011902; GA MŠMT VS97099; GA MŠMT OK 267
Grant - others:RFBR(RU) 98-04-48044; INTAS(BE) 2000-1147
Institutional research plan: CEZ:AV0Z5011922
Keywords : frog * desensitisation * miniature endplate potential
Subject RIV: ED - Physiology
Impact factor: 1.770, year: 2001

A new comparative characteristic of endplate microphysiology has been introduced. It is the feasibility of receptors to become desensitised as demonstrated on two frog species, Rana temporaria and Rana ridibunda: the decay times (tau(MEPC)) of single quantum miniature endplate currents (MEPCs) in the sartorius muscles of both species were about 1 ms and were not affected by the desensitisation-promoting agent proadifen when AChE was active. However, when the desensitisation was induced by anticholinesterase neostigmine and promoted by proadifen, the prolongation of tau(MEPC) from 1 ms was almost twice as great in Rana temporaria (tau(MEPC) = 4.4 ms) than in Rana ridibunda (tau(MEPC) = 3.1). This indicates that desensitisation reduces the number of available receptors and lowers the number of available ACh molecules for repetitive binding by trapping them by desensitised, high-affinity receptors significantly more in Rana ridibunda than in Rana temporaria. The application of proadifen, a promoter of desensitisation, decreased the prolongation of MEPCs in both species, but this shortening was more rapid in Rana ridibunda than in Rana temporaria. It is concluded that the desensitisation-induced reduction in the density, and the number of postsynaptic receptors is significantly higher at Rana ridibunda than in Rana temporaria endplates.
Permanent Link: http://hdl.handle.net/11104/0039848