Study On The Potential Mechanism Determination Of Erythromycin’s Different Inhibition Effects On HERG Channel At Room Temperature And 37℃

Erythromycin is a macrolide antibiotic widely used in clinical practice,but it may lead to some serious cardiotoxicity,such as QT interval prolongation,torsades de pointes（TdP）and even sudden cardiac death.The blockade of erythromycin on the potassium channel of the human ether-a-go-go-related gene（hERG）is an important mechanism of cardiotoxicity.Studies have shown that the inhibition at near-physiological temperature is stronger than that at room temperature（23±2℃）.So our experiment mainly studied the mechanisms of erythromycin on the cardiac hERG potassium channel at room temperature and 37℃.In this study,the whole cell patch clamp technique was used to study the potential mechanism determination of erythromycin’s different inhibition effects on h ERG channel at room temperature and 37℃.The conclusions are as follows:1.In this study,the whole cell patch clamp technique was used to detect the effects of erythromycin on hERG potassium channel.We found erythromycin cause a centration dependent inhibition of cardiac hERG potassium channels.The half maximal inhibitory concentration(IC₅₀)value is 1684μM（n=5）at room temperature and IC₅₀0 value is 150μM（n=7）at 37℃.The IC₅₀0 value at room temperature is about 10 times at 37℃.The inhibition rate of 3 mM erythromycin on hERG was 68±4.32%at room temperature,and the inhibition rate of 300μM erythromycin was 58±3.35%at 37℃.2.We used different pulse stimulation to detect the effects on hERG potassium channel current-voltage（I-V）curve,inactivation and recovery,under the conditions of 300μM erythromycin application at 37℃and 3 mM erythromycin application at room temperature.It was found that erythromycin can affect the activation and inactivation of hERG channels at room temperature and at37°C.3.Finally,five mutants,T623A,S624A,V625A,Y652A and F656A,were obtained according to the hERG conventional binding sites of the drug.T623 and V625 are the important role of sites at room temperature.T623,S624 and Y652 are the key sites at 37℃.It suggests that the mechanisms of erythromycin at room temperature and 37℃on hERG are significantly different.4.On this basis,we used a common hERG potassium channel blocker cisapride to study whether the temperature can have a certain effect on the channel,as a reference to the temperature dependence.The inhibitory effect of cisapride on hERG channel is not affected by temperature,while the mechanism of action of erythromycin at room temperature and 37℃is obviously different.The experiment for the first time systematically studied why erythromycin has different potency at room temperature and 37℃,and found a potential mechanism of erythromycin on hERG channel at room temperature and 37℃.Erythromycin is widely used in clinical,but the research on the mechanism of cardiotoxicity induced by erythromycin is not comprehensive.Therefore,to investigate the cardiotoxicity of erythromycin at room temperature and 37℃is of great significance not only for clinical application,but also for the study of cardiotoxicity of other structurally similar compounds.