The Participation Of TRPC In Myocardial APD Frequency Dependence And The Effect Of Antiarrhythmic Drugs On TRPC Expression

Classic transient receptor potential channel (transient receptor potential canonical, TRPC) including seven family members,TRPC1-7, is a class of calcium permeability of the non-selective cation channels, and cardiovascular system diseases are closely related with them, such as arrhythmias, sinusatrial block, they also play an important role in cardiac hypertrophy, cardiomyopathy and heart failure.The purpose of this experiment is to study The Participation of TRPC in myocardial APD frequency dependence and The effect of antiarrhythmic drugs on TRPC expression.Part1The Participation of TRPC in APD frequency-dependent of guinea pig papillary muscle Objective:To observe different frequency stimulation of guinea pig right ventricular the papillary muscle action potential APD changes with a frequency-dependent manner, and determination of whether TRPC protein expression changes under different stimulation frequencies.Method:Transmembrane action potential in the standard intracellular microelectrode recording technique, recording different stimulation frequencies (0.2Hz,0.5Hz,1Hz, 2Hz,3Hz,4Hz,4.5Hz,5Hz), papillary muscles APD changes.Use of the Western blot method, Determination of1Hz,3Hz,4.5Hz frequency papillary muscle specimens TRPC expression levels.Results:1. In the stimulation frequency of0.2Hz,0.5Hz,1Hz,2Hz,3Hz,4Hz,4.5Hz,5Hz, with the increase of the stimulation frequency, the transmembrane action potential of papillary muscle APD gradually shortened, showing obvious the frequency dependency.2. Compared with1Hz foundation stimulation frequency3Hz stimulation of guinea pig right ventricular papillary muscle action potentials process APD50, APD90were shortened (40.1±8.2)%,(33.7±6.3)%;4.5Hz stimulation of guinea pig right ventricular papillary muscle action potential process APD50, APD90were shortened (47.2±9.5)%,(44.1±7.3)%.3.Compared with1Hz basic stimulated group,3Hz and4.5Hz papillary muscle of TRPC1, TRPC3, TRPC6expression levels were significantly decreased, and exhibits the characteristics of corresponding frequency dependence, i.e. as the stimulus frequency increases, TRPC1,3,6expression level is decremented.Summary:Guinea pig papillary muscle action potential period showing a manner of frequency-dependent, with the addition of frequency, the cardiac action potential duration is shortening, at the same time, TRPC protein expression also changes, showing that there is a close correlation between them.Part ⅡThe effect of antiarrhythmic drugs on TRPC protein expression Objective:Observed that the frequency dependency of the different types of anti-arrhythmic action of the drug, and measuring the change in the amount of TRPC expression.Method:Transmembrane action potential standard intracellular microelectrode recording technology to record Nef,AM and Qd before and after administration of the papillary muscle action potential schedule APD50, APD90impact.TRPC protein expression of different administration and control groups was determined by Western blot.Results:1. With the stimulation frequencies1Hz,3Hz,4.5Hz conditions,Nef30μmol/L、AM10μmol/L and Qd5μmol/L can prolong the APD of guinea pig right ventricular papillary muscle, but the extension relative percentage (AAPD/APD) is different,1、3、4.5Hz, compared with pre-administration Nef30μmol/L longer APD90percentage (4.3±2.4)%,(14.3±3.6)%and (28.5±6.2)%, respectively, showing a positive frequency-dependent characteristics; AM10μmol/L longer APD90percentage were (17.1±2.4),(19.5±3.5),(15.9±6.7)%, performance of the non-frequency-dependent characteristics; Qd5μmol/L longer APD90percentage of (13.3±3.1)%,(5.7±1.7)%,(3.6±1.5)%, respectively, showing reverse frequency-dependent.2. Compared with the control group, Nef, AM and Qd group, papillary muscle TRPC1, TRPC3, of TRPC6expression were changed,TRPC protein expression of Nef group increase is significantly.Summary:1. Various antiarrhythmic drugs affect cardiac action potential frequency dependence in different ways. Nef30, AM10and Qd5μmol/L prolongation of the APD, respectively showed positive-frequency, non-frequency, reverse frequency dependent manner. 2. Different types of anti-arrhythmic drugs can affect TRPC protein expression, Nef30μmol/L significantly increased TRPC1,3,6protein expression, respectively, compared with the control group is2.26times,2.32times and2.34times.