细胞膜内外正常钠和钾浓度差的形成和维持是由于（ ）。

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SQL Error: select id,body,options from ***_enewstiku where sourceid='31197' and id < 2506886 and id<>'2506886' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='31197' and id > 2506886 and id<>'2506886' order by id asc limit 5