Microscopic Pathological Features Of Spasm Of Minute Collaterals Of Heart Disease

Objective: To investigate the microscopic pathological features of minutecollaterals of heart disease by studying the level of overall, organ, tissue, cell andmolecular pathology changes in model rats.Methods:(1) A total of30male Sprague-Dawley rats were random separated intothe control group, the5min group, the10min group, the20min group and the30mingroup. Constriction of minute collaterals model was made by injecting the pituitrinthrough femoral vein in rats. The myocardial blood flow of rats was measured byLaser-Doppler Perfusion Imager, and the degree of myocardial ischemic injury inrats was observed by Nagar-Olsen specific staining, and the changes of ultramicrostructure in myocardium were detected by transmission electron microscope.The protein expression of occludin and claudin-5was determined by Western blot.Another6healthy male Sprague-Dawley rats were selected to examine theinfiltration leukocyte of model rats.(2) The levels of ET-1, NO, AngⅡ, TXB2,6-Keto-PGF1αwere determined and the mRNA expression of iNOS, eNOS and ET-1in myocardial tissue was examined.(3) Cardiomyocyte apoptosis was detected withTUNEL staining. The protein expression of apoptosis and angiogenesis-related wasexamined in immuneohistochemical method.Results:1. The myocardial blood flow was less than that before modeling (P<0.05orP<0.01), and results showed a recovery trend with time extending. The positiveregions for Nagar-Olsen specific staining were observed in all model groups,especially in the10min and20min groups. Under the transmission electronmicroscope, lots of ultra microstructure changes such as tight junctions betweenmicrovascular endothelial cells were dense clearly, microvascular endothelial cellapoptosis was observed and pinocytotic vesicles significantly increased in all themodel groups. And apparent leakages were observed in the rats after10min of modeling.2. The level of plasma ET-1in all the model groups was significantly increased(P<0.01), and reached the peak at5minutes. The level of plasma TXB2wassignificantly increased in the5minutes group (P<0.01), and significantly decreasedin the30minutes group (P<0.05). The level of plasma6-keto-PGFlαwassignificantly decreased after10minutes of modeling (P<0.05), and reached the lowpeak at30minutes (P<0.01). TXB2/6-keto-PGF1αwas significantly increased from5minutes to20minutes after modeling (P<0.01or P<0.05), and reached the peak at5minutes and then return to the normal level in the30minutes. The level of AngⅡwithin5minutes after modeling showed no significant changes, but dramaticallyincreased from10minutes (P<0.05), and showed an increasing trend and reached apeak at30minutes (P<0.01). And compared with control group the level of NO inmodel groups were increased significantly (P<0.01). The mRNA expressions ofiNOS in myocardial tissue were significantly increased in the5min group and10min group (P<0.01), and significantly decreased in30min group (P<0.01). And themRNA expressions of eNOS in the model groups were significantly decreasedcompared with the control group (P<0.01). On the contrary, the mRNA expressionsof ET-1in the model groups were increased in varying degrees.3. Compared with control group the apoptosis index in model groups increasedsignificantly. The prolongation of ischemic time and the number of apoptotic cellsgradually increased. Compared with control group, the protein expression of Baxincreased20minutes after modeling. The protein expressions of Bcl-2had noobvious changes in the model groups. And the protein expression of p53increasedsignificantly (P<0.05). Compared with the control group, the protein expressions ofCD34, VEGF, PDGF, Ang2in model groups had no changes (P>0.05).Conclusions:1. A prominent decrease of myocardial blood flow occurred in acute stageof the spasm of minute collaterals.2. The myocardial microvascular permeability apparently increased in acutestage after the spasm of minute collaterals. The tight junction of microvascular endothelial cell was dense clearly, the tight junction protein had a normal expression,and the number of pinocytotic vesicles increased apparently after modeling, whichindicate that the increase of permeability myocardial microvascular though releasinglarge amount of pinocytotic vesicles in acute stage of the spasm of minutecollaterals.3. The secretion of microvascular endothelial cells was dysfunctional in theacute stage of the spasm of minute collaterals, which induced the abnormal secretionof TXA2, PGI2, ET-1and NO. The renin-angiotensin system (RAS) was activatedand played a vital role in aggravating the damage of myocardial. All these changesindicated that a variety of complex mechanisms were involved in the induction of thespasm of minute collaterals.4. Apoptosis was increased by regulating the expression of apoptosis-relatedproteins in acute stage of the spasm of minute collaterals.5. There was no obvious angiogenesis in the stage of the spasm of minutecollaterals.