Preliminary Research On Effects Of Carbon Nanomaterials On Cardiac Function And Its Mechanism In Rats Based On Calcium Signaling Pathway

Carbon Nanotubes,as one of the most important nanomaterials,they are mainly carbon nanotubes,nano-carbon spheres,carbon Nano-cellulose and graphene.Because of its potential advantages,carbon nanomaterials have broad application prospects in medicine and health,biomedicine and other fields.Graphene oxide(GO)and single-walled carbon nanotubes(SWNTs),as derivatives of new carbon nanomaterials,have become the focus of many scientists around the world.With the wide application of SWNTs and GO in various fields,the potential biological toxicity of SWNTs and GO has attracted more and more attention.Researchers have conducted a lot of experimental studies on their biological toxicity at animal,cell and molecular levels.Because SWNTs and GO are ultrafine particles,intravenous injection is the main method of administration.A large number of studies have shown that SWNTs mainly accumulate in liver,kidney and lung after they enter the blood circulation system.However,there are few and unclear studies on its cardiotoxicity and its mechanism.Therefore,we chose C-carboxylated single-walled carbon nanotubes(C-SWNTs)and GO as the subject investigated,SD rats as the experimental animals,injected C-SWNTs and GO into rats through tail vein,and used YM-58483(BTP2),a calcium influx blocker controlled by selective calcium pool,to preliminarily study the cardiotoxicity and mechanism of intravenous SWNTs and GO,so as to provide a toxic basis for the biomedical application of C-SWNTs.Objective: 1.To evaluate the effects of C-SWNTs and GO on blood pressure and cardiac function in SD rats.2.The ultrastructural changes of the heart were observed by transmission electron microscopy,and the pathological changes of the heart were evaluated by pathological sections.3.To explore the mechanism of carbon nanomaterials on cardiac function in rats based on calcium signaling pathway.Methods: 1.The preparation of C-SWNT and characterization of before the animal experiment: Pre-experimental characterization of C-SWNTs and GO in animals: the morphology of C-SWNTS was observed by transmission electron microscopy(TEM),the surface groups of C-SWNTs and GO were detected by laser tweezers Raman spectrometer(LTRS);the metal content of C-SWNTs and GO dispersions was detected by inductively coupled plasma atomic emission spectrometer(ICP-AES),and the concentration of C-SWNTs was determined by ultraviolet-visible spectrophotometer(UV-Vis).2.Animal experiment grouping and cycle setting: 50 healthy 6-week-old female and 50 male SD rats were selected,totally 100 rats.They were randomly divided into five groups: blank control group,C-SWNTs experimental group,GO experimental group,C-SWNTs + YM experimental group and GO + YM experimental group.Setting two administration cycles of 7 days and 30 days respectively.At the end of each administration cycle,10 rats were randomly selected from each group,50 of them were male and female,and entered the next step of tail artery pressure measurement,left ventricular pressure,color Doppler echocardiography and anatomical experiments to prepare samples.3.To evaluate the effects of C-SWNTs and GO on blood pressure and cardiac function in SD rats: The changes of blood pressure,blood flow velocity and left ventricular functionwere observed by non-invasive tail artery manometer and color Doppler echocardiography.4.To observe the changes of ultrastructure and pathomorphology of heart: the changes of ultrastructure of heart in SD rats were observed by TEM,and the pathological changes of heart in SD rats were evaluated by hematoxylin-eosin staining(HE staining).5.The mechanism of cardiotoxicity of C-SWNTs and GO based on calcium signaling pathways: Western Blotting was used to evaluate the expression of STIM1,Orai-1 and ERK1/2.Results: 1.After carboxylation of SWNTs,C-SWNTs and GO had good dispersion in water.TEM observation showed that the size distribution of C-SWNTs and GO was uniform and less aggregated.The IG/ID values of C-SWNTs and GO ware 0.78 and 1.2,respectively.ICP-AES results showed that the contents of Fe,Co,Al,Cr,Cu and Ni in c-SWNTs and GO samples used in animal experiments are low.2.After injecting C-SWNTs and GO glucose dispersions via tail vein,rats’ tail artery blood pressure was increased and YM could effectively reduced the tail artery hypertension induced by C-SWNTs and GO.It was found by color Doppler echocardiography that C-SWNTs and GO could decrease left ventricular systolic function and accelerate the maximum flow velocity of pulmonary aortic valve orifice in rats.The same YM could decrease left ventricular pressure in rats caused by C-SWNTs and GO by MAP cardiac function meter.Similarly,YM can reduce left ventricular hypertension.It was aggravated with the increase of administration cycle,which was cycle-dependent.3.TEM results of rat heart slices showed that in the blank control group,nucleoli were obvious,organelles were abundant,edges were clear,muscle filament structure was clear,arranged neatly,mitochondria were evenly distributed on both sides of muscle filament,and capillary network structure was complete without obvious pathological changes.In C-SWNTs and GO groups,the cell nucleus were pyknosis,irregular shape,nuclear membrane folds,the number of mitochondria increased,the structure was damaged,and a large number of vacuoles appeared in the cytoplasm.C-SWNTS and GO were found in intercellular and capillary vessels,and capillary wall was thickened.In addition,the myofilament structure of 30 days C-SWNTs group was observed to be vague and amorphous,and intercalated discs were agglomerated.HE staining of rat heart slices under optical microscope showed that a large number of inflammatory cells infiltrated around the portal vessels of C-SWNTs and GO administration groups,accompanied by fibrosis and vessel wall thickening,resulting in vascular stenosis,and aggravated with the increase of administration cycle,which was cycle-dependent.4.Western Blotting showed that the expression of calcium signaling pathway related proteins(STIM1,Orai-1)and ERK1/2in heart tissue was significantly up-regulated.Conclusion: 1.C-SWNTs and GO have cardiotoxic effects on rats,which lead to elevated blood pressure and cardiac insufficiency,and accelerate the blood flow velocity of pulmonary and aortic valve orifices.2.YM can effectively inhibit the abnormalities of cardiac function and blood flow velocity induced by C-SWNTs and GO.Its mechanism is related to the inhibition of STIM1,Orai-1 and ERK1/2 protein expression in calcium signaling pathway.