The Effects Of Succinylcholine On Adult-type And Fetal-type Muscle Nicotinic Acetylcholine Receptors Transiently Expressed In HEK293 Cells

Objective: In order to explore why succinylcholine produced critical hyperpotassemia in some pathological state, we compared the effects of succinylcholine at the fetal- and adult-muscle acetylcholine receptor (y- and s-nAChR) transiently expressed in HEK293 cells.Methods: 1. The cDNA coding for the a , (3 , 6 , y ?e -subunits of the mouse muscle nAChR in pSP65. pSP64. pBS SK(-) are subcloned into pcDNAS. T by gene recobinant technique and then transfected HEK293 cells with pcDNAS.T a , pcDNA3.T P , pcDNA3.1+5, pcDNAS.T Y or pcDNA3.1+ e in the ratio of 2:1:1:1 by lipofection technique. Identifing the expression of y-nAChR and e-nAChR by whole-cell patch clamp technique. 2. (T) Recording and comparing the response of y-nAChR and e-nAChR to succinylcholine and acetylcholine by using the whole- cell clamp technique. (2) Appling succinylcholine for 600s and recording the current, comparing the time-response curve. Results: 1. A inward current was recorded when appling acetylcholine to transfected HEK293 cells. The m-nAChRs expressed in HEKk293 cells successfully. 2. ?Short succinylcholine application: The ECso of acetylcholine was 13.1 u M and 18. 6 u M for y-nAChR and e-nAChR (P>0. 05) ; The EC50 of succinylcholine was 58.3 n M and 75. 9 u M for y-nAChR and e-nAChR ( P>0. 05) . Succinylcholine are less potent for y-nAChR and E-nAChR than acetylcholine ( R0. 05 ) , The EC50 of succinylcholine for two nAChR is almost one forth as acetylcholine.(2) Long succinylcholine application: The current decay was different betweeny-nAChR and e-nAChR after application of succinylcholine. The former was slower, the latter was more rapid. When acetylcholine was co-applied in current decay phase, the current did not vary.Conclusions: (1) Succinylcholine activate both y-nAChR and e-nAChR , and was less potent than acetylcholine; (2) The slower current decay of y-nAChR may result in hyperpotassemia in some pathological state; (3)The more rapid desensitizat ion of e-nAChR may result in residual relaxation effect of succinylcholine.