Effective Of Verapamill On HEGR Current And Guinea Pig Papillary Muscles Action Potentials

Verapamil can prevent the occurrence of ascites and reduce the ascites heart index has been demonstrated,which is beneficial to prevent right heart hypertrophy and functional failure of broilers,and can protect the heart and other important organs in hemorrhagic shock dogs.In this study,the effect of verapamil on the h EGR-related genes current and action potential in cardiomyocytes was analyzed by patch clamp technique and action potential technique.In order to provide reference for the ion pathway study and safety evaluation of the drug.The following results are obtained:1、The human embryonic kidney cells stably expressing h EGR channels were used in the study.A Multi Clamp 700B manual patch clamp system was used to induce and record h EGR currents in whole-cell voltage clamp mode.Pimozide at0.001,0.01,0.1and1μmol/L or Verapamil at 0.1,1,3 and 10μmol/L were delivered separately to the clamped cells by a6-channel perfusion system.The h EGR channel tail currents were recorded by clampex 10.3.The data were collected and analyzed by clampfit 10.3.The peak of the tail currents in the presence of positive control and test article were normalized with the currents recorded in the presence of corresponding vehicle control as 100%respectively.The IC₅₀value was calculated using Graphad Prism 5.00.The results indicated that Pimozide at 0.001,0.01,0.1and 1μmol/L inhibited the h EGR currentsin a concentration-dependent manner.The IC₅₀value of Pimozideis 0.01672μmol/L.Under the same condition,the Verapamil at 0.1,1,3and 10μmol/L inhibited the h EGR currents in a concentration-dependent manneras well with IC₅₀value of 0.2981μmol/L.2、The acute isolated papillary muscles from guinea pig right ventricle were used in this study.The papillary muscles were perfused with oxygenated（95%O₂-5%CO₂）modified Tyrode’s solution at 35℃at a speed of 5 ml/min constantly.The papillary muscles were stimulated with rectangular pulses of 2 ms duration and 1.5 times-threshold strength to induce action potential.Modified Tyrode’s solution containing Pimozide at 0.01,0.1,1 and3μmol/L or Verapamil at 0.01,0.1,1 and 10μmol/L were delivered to the papallary muscles by perfusion system.The action potentials were recorded by Lab Scribe 2 software,and the effects of Verapamil/Pimozide（positive control）on APD₃₀,APD₉₀and APD_30-90of papillary muscles in Guinea pigs were analyzed by Lab Chat 7.Ccompared with vehicle,Pimozide prolonged APD₃₀,APD₉₀and APD_30-90in a concentration-dependent manner at concentration of 0.01,0.1,1 and 3μmol/L.The percent prolonging induced by Pimozide at the highest concentration 3μmol/Lin this study were 95.408%for APD₃₀,78.954%for APD₉₀and 47.173%for APD_30-90.Compared with vehicle,Verapamil shorten APD₃₀,APD₉₀and APD_30-90in a concentration-dependent manner at concentration of 0.01,0.1,1and 10μmol/L.The percent shortening induced by Verapamil at the highest concentration10μmol/Lin this study were-63.384%for APD₃₀,-44.070%for APD₉₀and-20.171%for APD30-90.This study demonstrated that Pimozideand Verapamil inhibited the h EGR currents of HEK-293 cell in a concentration-dependent manner.Pimozide prolonged action potential duration of guinea pig papillary muscles in a concentration-dependent manner while Verapamil shorten action potential duration of guinea pig papillary muscles in a concentration-dependent manner.