Effects of chymostatin on ventricular arrhythmias in rat with myocardial ischemia reperfusion in vivo
Abstract：Objective To investigate the effects of chymostatin ( a chymse inhibitor ) on the susceptibility of rat to ventricular arrhythmias ( VA) in an ischemia reperfusion ( IR) model in addition to attenuate myocardial injury .Methods Rats were subjected to left coronary artery occlusion for 20 min followed by 20 min reperfusion and received pretreatment with saline ( IR group ) or chymostatin (Chymostatin group) intraperitoneally 30min before ischemia.Elecrocardiogram and monophasic action potentials were recorded and analyzed for heart rate , 90% repolarization of action potential duration ( APD90 ) and APD dispersion ( APDd ) .A VA score system was used to test susceptibility of VA . Renin, angiotensinⅡ( AngⅡ), angiotensin converting enzyme ( ACE) and chymase activities were assayed.Chymase expression in myocardial tissue was determined by immunofluorescence staining . Results Myocardial ischemia resulted in VA , APD90 shortening and APDd enlargement .Pretreatment with chymostatin could reduce VA score , APD90 shortening and APDd enlargement ( P <0.05 ). Chymostatin pretreatment significantly reduced AngⅡlevel and chymase activity in ischemic myocardial tissue ( P <0.05 ) without altering ACE activity and plasma Ang Ⅱ level ( P <0.05 ). Immunofluorescence staining also revealed chymase increased in myocardial tissue of IR group and partly attenuated of chymostatin group . Conclusion The present study demonstrated that Chymostatin ameliorated APD dispersion and ischemic VAs , and its mechanism may be correlated with chymse -dependent AngⅡproduction .
Keywords：Myocardial ischemia reperfusionVentricular arrhythmiaMonophas action potentialsChymaseChymostatinAngiotensinⅡAngiotensin converting enzyme
Publication Date：2015-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：5( 934-938 )