Adult Cardiac Conduction Department Of Morphology And Of Cx43, Connexin40 Expression

Objective (1)To observe the location,morphous,cell component ,the construction of cardiac muscle fibers and the expression of connexin43,connexin40 at every part of normal adult cardiac conduction system. And then to provide some more morphological basis for the study on the cardiac electrophysiology.(2)To observe the morphological feature of some spots that related to common arrhythmogenesis and radiofrequency ablation(RFA),and then to provide some morphological basis for the mechanism of arrhythmogenesis and possible sites for therapy.Materials and Methods Take some parts related to the cardiac conduction system of 10 fresh normal adult hearts preparation that has been confirmed have no cardiac diseases by gross anotomy. Make consecutive tissue slice in three directions,that is longitudinally,intersect and level,then make HE stain,Masson stain and immunohistochemistry stain of connexin43,connexi-n40.To observe with light microscope and make image analysis.Results (1)There are differences of cell component,assignment , courser and association of fibers between ordinary cardiac muscles and ingredients of normal adult cardiac conduction system and the bundle of transition cells located at atrioventricular junction,crista terminalis,myocardial sleeves of the pulmonary veins and cavo-tricuspid isthmus.(2)The expression of connexin40 is more than that of connexin43 at cardiac conduction system,especially at the proximum such as SAN and AVN. The positive staining is located at cytolymph and cellular membrane. In the cross section,the positive staining is diffused distributed uniformly. And in the longitunal section,the positive staining is maldistributed,most align along the long axis of the cells in chains and also some located at intercalary disc.(3)The expression of connexin43 and Connexin 40 and the colour of endochylema becomes less gradually from the common atrio-muscle to the periphery of SAN and to the center of SAN. The expression area of connexin40 is to go against to the general change tendency,presented as the positive area at the center of SAN is larger than the periphery. The expression of connexin43 and connexin40 at AVN follows the change tendency,that is body>stern>head.The expression of Cx43:periphery>superficial band> deep band ,and Cx40:periphery>pykno-AVN.But the expression of connexin43 at the small distribution area at stern of AVN is intensive,and the expression of connexin40 at the distribution area at the part of AVN that goes into the CFB is intensive.Cx43 and Cx40 co-express at His bundle,LBB,RBB and purkinje fibres,and the GJ particle is comparatively large. The distribution of Cx43 and Cx40 at bundles 1 -4 of transition cells and annulus of right atrium upper-vavle muscles is localized at a small area but intensive,and in the transition cells of left atrium close to the membranous part of interventricular septum the distribution is comparatively plentiful. The endochylema staining with HE stain in the transition cells in the deep direction of SAN and AVN is deeper than them,and light than atrium muscle. The expression of Cx43 and Cx40 at these areas is more than that at SAN,AVN and atrium muscle. The distribution of Cx43 and Cx40 at myocardial sleeves is more intensive than that at the other part of the pulmonary veins and normal atrium muscles,and the endochylema staining with HE stain is among them. The expression range of Cx43 and Cx40 at cavo-tricuspid isthmus is large,and the distribution is intensive.Conclusion (1)The expression of Cx43 and Cx40 varies in different part of cardiac conduction system,that is the expression at the proximal end is less than that at the distal end,center of SAN and AVN is less than the periphery.(2)There are the bundle of transition cells around the open of coronary sinus and at its distal end,at cavo-tricuspid isthmus,anulus fibrosus of bicuspid valve,and the CFB near the annulus of right atrium upper-vavle muscles. And the bundles connect with AVN and PNE in different directions.(3)There are P-like cells at crista terminalis, myocardial sleeves of the pulmonary veins , cavo-tricuspid isthmus and the annulus of right atrium upper-vavle muscles,and the distribution of Connexin at these areas is uneven.(4)There are the bundle of transition cells that can be identified in morphology between SAN and AVN.