烟碱受体在非洲爪蟾卵母细胞的表达及特征

分别给非洲爪蟾卵母细胞微量注射电线电器官烟碱型胆碱受体（Ｎ＿２－ＣｈＲ）和大鼠脑烟碱型胆碱受体（Ｎ＿１－ＣｈＲ）的ｍＲＮＡ，表达出相应的Ｎ－ＣｈＲ。采用全细胞和部分细胞灌流法测定不同浓度氨甲酰胆碱引起的Ｎ＿２－ＣｈＲ产生的膜电流，以最小反应模型方程拟合两法所得量反应曲线非常接近。Ｋ＿１值分别为０．５２８和０．４９１ｍｍｏｌ·Ｌ￣（－１）；Φ￣（－１）值分别为３．８６１和３．８９１。采用全细胞灌流法测得不同浓度氨甲酰胆碱引起的表达Ｎ＿１－ＣｈＲ产生的膜电流，拟合所得的量反应曲线较之相应的Ｎ２－ＣｈＲ曲线明显左移。Ｋ＿１和Φ￣（－１）值分别为０．１４０ｍｍｏｌ·Ｌ￣（－１）和３．１２５。

Expression and characteristics of nicotinic receptorsin Xenopus oocytes

Torpedo electroplax nicotinic recep-tor (N_2-ChR) and rat brain nicotinic receptor(N_1-ChR) were synthesized in Xenopus oocytes after injec-tion with mRNAs transeripted in vitro from plasmidspSP64T containing the four full length TorpedoN_2-ChR subunit cDNAs or purified from yeast trans-ferred with rat brain N_1-ChR α4 and β2 subunitcDNAs. Membrane current in the inlected oocytes wasmeasured with voltage clamp technique by part cellflow and / or whole cell flow with various concentra-tions of carbamylcholine, the dose responses tocarbamylcholine were similar. K_1 of 0.528 and 0.491mmol·L-1, Φ-1 of 3.861 and 3.891 were obtained inoocytes inJected with Torpedo N_2-ChR mRNA bywhole cell flow and part cell flow, respectively. Adose-response curve shifted to left but similar to whatis obtained from Torpedo N_2-ChR. a K_1 of 0.140mmol·L-1 and a Φ-1 of 3.125 were obtained in theoocytes injected with rat brain N_1-ChR by whole cellflow.