Phenytoin Can Accelerate The Healing Process After Myocardial Infarction In Rat And In Vitro

Objective To investigate the connective tissue-proliferating characteristics of phenytoin in the wound healing process after acute myocardial infarction . Methods In vivo study was performed on rat model of acute myocardial infarction .Surviving rat were randomly divided into different treatment groups: phenytoin (100mg-Kg-1 day-1 ip) , captopril (2g/L in dinking water ad libitum) , phenytoin plus captopril , operation control and sham operation .On the 14th day after operation ( half of the controls were killed on the 21th day ) , rats were sacrificed .Hearts were removed and prepared for histological analysis .Picrosirius red staining plus polarized light microscopy was used for qualitative and quantitative analysis of collagen accumulation , cross-linking in infarcted and non-infarcted region of heart tissue slides .We also detected TCP-Pi, Smad2/3, Smad4, Smad? protein expression in different region of heart tissue slide by immunohistochemisty. Neonatal rat cardiac fibroblast and adult rat peritoneal macrophage primary culture were performed as in vitro part . We tested the effects of phenytoin concentration gradient (0ug/mL , 1.25ug/mL , 2.5ug/mL, 5.0ng/mL, 10.0ug/mL, 20.0ug/mL) in culture media on cellular toxicity , proliferation , TGF -B1 production and soluble collagen secretion of cardiac fibroblast and possible mechanisms mediated by macrophage, using the ELISA, MTT and biochemical assay .Results Phenytoin has little direct effects on neonatal rat cardiac fibroblast proliferation and extracellular matrix synthesis abilities in vitro , but pre-stimulated macrophage by phenytoin can exert a positive influence on cardiac fibroblast bioactivities and present a dose-dependent manner (r = 0.865 and r = 0.816, P < 0.05) . Phenytoin can increase collagen intermolecular cross-linking level (Phenytoin 130.19?2.09 v.s. operation control111.44+10.33 (gray scales), P<0.01) and ratio of type I /IE collagen in the infarcted region , which is comparable to those of 21 days after myocardial infarction. Notably, phenytoin do little to collagen volume fraction, subtype ratio and distribution in non-infarcted region .14 days after myocardial infarction, phenytoin did not elevate total TCP-B1 and R-Smad, Co-Smad protein levels in infarcted region .Conclusion For the first time , we demonstrated that by indirectly stimulating effects on macrophage , phenytoin can hasten the healing process in the infarcted region and has no obviously detrimental influence on collagen accumulation in non-infarcted septum and right ventricle in our investigating period , which implies an potential benefits on patients undergoing early post-infarction ventricular remodeling process.