摘要
目的研究高血压大鼠左室流出道自发性慢反应电位0相和4相去极离子流。方法利用自发性高血压大鼠(SHR)的离体心脏,常规玻璃微电极细胞内记录方法和离子通道阻断剂,观测最大舒张电位(MDP)、0相除极幅度(APA)、0相最大除极速度(Vmax)、4相自动除极速度(VDD)、复极50%(APD50)和90%(APD90)的时间以及自发放电频率(RPF)。结果(1)1·2mmol/L河豚毒(TTX)使APA和Vmax与给药前相比有所减小(P<0·05),VDD和RPF明显减慢(P<0·01);(2)1·0μmol/L维拉帕米(VER)可使该慢电位的APA、Vmax、VDD明显减小,RPF减慢(P<0·01);APD、APD90延长(P<0·05);(3)2mmol/L4-氨基吡啶(4-AP)使该慢电位的MDP的绝对值、APA、Vmax减小,VDD和RPF加快,与给药前相比有显著差异(P<0·01);(4)1·5mmol/L CsCl作用6min时,VDD和RPF明显降低(P<0·05),10min时恢复。结论(1)左心室流出道的自发慢电位0相主要去极离子流除Ca2+内流外,还有少量Na+内流。(2)4相去极离子流中,除Ca2+、Na+的内流和Ik衰减外,If电流可能也起部分作用。
Objective To analysis the ionic mechanism underlying the phase 0 and phase 4 for the slow-response action in left ventricular outflow tract in spontaneous hypertensive rats. Methods Spontaneous slow action potentials of the left ventricular outflow tract were intracellularlly recorded with conventional microelectrodes. Electrophysiological parameters are： maximal diastolic potential （MDP）, amplitude of action potential （ APA）, maximal rate of depolarization of phase 0 （ Vmax ）, velocity of diastolic depolarization of phase 4 （VDD）, duration of 50% and 90% repolarization （API）50 and APD90） and rate of pacemaker firing （RPF） . Results （1） 1.2 mmol/L tetrodotoxin （TTX） significantly decreased APA and Vmax （P〈0.05）. VDD and RPF were significantly slowed down as compared with control （P〈 0.01）. （2） 1.0μmol/L verapamil （VER） significantly decreased APA, V VDD and RPF, （P〈0.01）, with APD and APD90 significantly prolonged. （3） 2 mmol/L 4-aminopyridine （4-AP） decreased MDP, APA and Vmax（P〈0.01）, while VDD and RPF was increased（ P〈0. 01）. （4）1.5 mmol/L CsCl perfused 6 min significantly decreased the VDD and RPF（P〈0.05）. Conclusion The data suggest that： （1） Generation of 0 phase of depolarization of slow-response activity in aortic vestibule from spontaneous hypertensive rats was mainly mediated by Na^＋ current and Ca^2＋ . （2） In addition to the inward Ca^2＋ and Na^＋ current and attenuated K^＋ current, Ifcurrent also plays some role in phase 4 depolarization.
出处
《高血压杂志》
CSCD
北大核心
2005年第9期568-572,共5页
Chinese Journal of Hypertension
