Study On Effect Of Nano Zinc Oxide On Cardiac Bioelectric Activity In Rats And Its Mechanism

Nano zinc oxide is a more superior material in nano-family, particle size in therange1-100nm, with dual properties of nano materials and traditional zinc oxide, theapplication prospect is very broad, and become one of the hotspots of medicalbiology.Zinc oxide itself is not toxic, but zinc oxide particles are harmful. Clinical andepidemiological survey found that occupational exposure to zinc oxide dust cloudsthat can cause flu-like acute respiratory inflammatory disease-metal fume fever(MFF),the performance of the lung or respiratory system inflammatory reaction, havea negative impact on human health. These particles have greater toxicity not only initself, and having nanoscale physicochemical properties, and having a negative impactto human body health. Dysfunctions caused by the body after entering the bodythrough breathing, have a negative impact on the cardiovascular system.Studies have shown that nanoparticles can through the hair follicles, retractableor injured skin penetration. Therefore, nano-zinc oxide may have a stronger toxicity,which makes nano-ZnO health hazards and ecological security caused widespreadconcern. Sharma V and other studies have shown that low concentrations of nano-zincoxide, causes skin cells to produce genotoxic potential of lipid peroxidation andmediated by oxidative stress. For example, in Australia, nano-zinc oxide sunscreeningredients on as widely used, there are over25million people have been diagnosedwith non-melanoma skin cancer each year, and more than8,000human melanoma.Liu Zihong, who studied the acute toxicity of nano-zinc oxide in mice by intratrachealinstillation way, the study found that with increasing doses of nano-zinc oxide, lung inflammation and proliferative changes increased. Cheng Wu studied by intragastricroute30nm zinc oxide particles on the acute toxicity in mice showed that high dosesof nano-zinc oxide can damage the kidneys and liver and other organs, but study ofnano-zinc oxide on the cardiovascular system are not reported.This paper use nano zinc oxide as the research object, observe the effect of nanozinc oxide on cardiac bioelectric activity in rats, we will use the electrophysiology andpatch clamp methods to observe the effect of nano zinc oxide on the whole animalheart rate, myocardial contractility in vitro and isolated cardiomyocytes actionpotential and sodium, calcium ion channels, and clarify the role of nano zinc oxide onmyocardial cells and its electrophysiological mechanisms, and provide a theoreticalbasis for clinical application.The main results are as follows:1. It can be seen in the overall of nano zinc oxide on rat experiments. Comparedwith the control group, in the10-6M concentration range of nano zinc oxide, rat heartrate does not occur, in the10-5M and10-4M concentration range of nano zinc oxide,rat heart rate slowed down, respectively, by550.23±47.26beats/min down to451.25±40.13and373.22±38.77times/min.2. On the organ level observed,10-5M and10-4M of nano-zinc oxide cansignificantly reduce the amplitude of myocardial contractility, decreased myocardialcontractility, compared with the control group, respectively, decreased from100%to94.34±5.12and85.66±6.53%.3. On the cellular level observed: in the10-6M concentration of the actionpotential of nano zinc oxide did not change significantly, in the10-5M and10-4Mconcentration of the nano zinc oxide can decrease action potential amplitude andreduce the action potential schedule shortened. In the10-6M concentration of nanozinc oxide, the peak current of sodium and calcium does not changesignificantly,10-5M and10-4M peak current INaby the nano zinc oxide compared with the control group were reduced to-76±6.2pA/pF-67±5.6pA/pF (P <0.05) and-61±5.3pA/pF (P <0.01, n=6). the peak current of10-5M and10-4M nano-zinc oxideICacompare with control group were reduced to-3.35±0.32pA/pF-2.87±0.25pA/pF (P <0.01, n=6) and-2.54±0.21pA/pF (P <0.001, n=6).In conclusion we draw the following conclusions: Zinc oxide in the10-6-10-4Mconcentration range, the heart rate slows down, weakening myocardial contractility,and affect myocardial cell electrical activity. The mechanism may be by decreasingsodium and calcium channel currents of rat ventricular myocytes, reducing actionpotential amplitude, shortening action potential duration.