Protective Effects Of Dextran-40 On Fatal Jellyfish Stings And Intervention Of Cations On Hemolysis Of Jellyfish Venom

Jellyfish,a class of invertebrate zooplankton,were distributed in marine ecosystems around the world.Ⅰn recent years,the increase in ocean temperature and the continued spread of coastal eutrophication have sometimes caused the outbreak of particular species of jellyfish in certain waters.Although most of them are harmless,some jellyfish contain toxins which could be released once they were stimulated by chemical or mechanical factors and contribute to severe jellyfish stings.There are more than thousands of people who were subjected to jellyfish stings every year,and even some people were died from jellyfish envenomation.Stings from different species of jellyfish result in different symptoms.Some people suffer from only a slight tingling or local swelling,while some bear with persistent pain,urticaria and blisters,epidermal necrosis,circulatory system damage,multiple organ dysfunction,and even death.More and more attention has been paid to the prevention and treatment of jellyfish stings.Some progress has been made,but there is still no consensus on the treatment measures for jellyfish stings.Jellyfish toxins are a mixture of complex composition with the disadvantages such as adhesion and rapid deactivation,and have diverse toxic targets.These physicochemical properties added difficulty to the efforts finding antagonistic drugs.Ⅰn the first part of this paper,the protective effects of Dextran-40 on fatal jellyfish stings were analyzed at the cellular and whole animal levels.The second part focused on the intervention effects of five metal cations on the hemolysis of jellyfish venom.Methods:Part Ⅰ: Protective effects of Dextran-40 on fatal jellyfish stingsⅠn this part,firstly,the protective effects of Dextran-40 on cardiomyocytes and erythrocytes against the damage induced by tentacle extract（TE）from the jellyfish Cyanea capillata were studied at the cellular level by laser scanning confocal microscopy.Ⅰn addition,using the fatal jellyfish envenomation syndrome（acute jellyfish envenomation syndrome,AJES and delayed jellyfish envenomation syndrome,DJES）models which were set up earlier,we detected the effects of Dextran-40 on the survival rate of AJES mice,on the circulatory function of AJES rats and on the serum biochemical indexes of DJES rats.Part Ⅱ: Ⅰntervention effects of cations on hemolysis of jellyfish venomFirstly,the hemolytic effect of TE and anti-hemolytic effect of five cations(La³⁺,Mn²⁺,Zn²⁺,Cu²⁺ and Fe²⁺)which have generally been reported to prevent jellyfish venom-induced hemolysis through multiple mechanisms were detected by spectrophotometry.And then,we determined the absorbance values of the five cation solutions and the influence of five cations on the absorbance characteristics of erythrocyte suspension and hemoglobin solution.We also counted erythrocytes under the microscope.Results:Part Ⅰ: Protective effects of Dextran-40 on fatal jellyfish stingsThe results showed that TE increased intracellular Ca^<sup>2+ content of cardiomyocytes and erythrocytes and decreased the number of cardiomyocytes and erythrocytes in a dose-dependent way,while Dextran-40 suppressed the TE-induced negative influence on Ca^<sup>2+ content and cell viability.Although Dextran-40 did not play a protective role against TE-induced damage to erythrocyte morphology,it effectively inhibited the TE-induced intracellular Ca^<sup>2+ overload.At the whole animal level,Dextran-40 at 0.8 g/kg significantly improved the survival rate of AJES mice,and at 0.6 g/kg greatly inhibited the drop of blood pressure of AJES rats.For the DJES rats,Dextran-40 at 0.6 g/kg had a significant protective effect on the liver function indexes（ALT,AST,A/G）and the myocardial enzymes（CK,LDH）.Part Ⅱ: Ⅰntervention effects of cations on hemolysis of jellyfish venom The colorful Zn²⁺,Cu²⁺ and Fe²⁺ cations resulted in a decrease in the absorbance values of the erythrocytes,while Mn²⁺ increased the absorbance values and the transparent La³⁺ had little effect,suggesting that the cation colors might interfere with the absorbance spectrum of hemoglobin.Then we tested the effects of cations on the released hemoglobin from erythrocyte suspension.We did not see any effect by the transparent La³⁺ on the hemoglobin solution.The Mn²⁺ solution displayed a small decrease in the absorbance values,while the colorful Zn²⁺,Cu²⁺ and Fe²⁺ greatly diminished the absorbance values of hemoglobin.After correction,La³⁺ showed a complete inhibition of TE-induced hemolysis,while the inhibition curves of Cu²⁺,Zn²⁺ and Fe²⁺ were shifted to the right,that is,Cu²⁺,Zn²⁺ and Fe²⁺ were actually less effective in inhibiting jellyfish venom-induced hemolysis than that previously reported.These corrected results were supported by a direct counting of erythrocytes under microscopy.Conclusions:Part Ⅰ: Protective effects of Dextran-40 on fatal jellyfish stingsWe speculate that there are at least two potential mechanisms understanding the protective effects of Dextran-40 on fatal jellyfish stings.One is that Dextran-40 is capable to block the TE-induced pore formation in the cardiomyocytes,leading to its ability to suppress Ca^<sup>2+ overload induced by TE.The other is that Dextran-40 makes it possible to antagonize TE-induced hypotension and other heart diseases,by upgrading the colloid osmotic pressure of plasma,increasing blood volume and stabling blood pressure.Part Ⅱ: Ⅰntervention effects of cations on hemolysis of jellyfish venomAll the tested five cations,except the transparent La³⁺,were found to significantly influence the erythrocyte test systems and the absorbance characteristics of hemoglobin by virtue of their colored aqueous solutions.Therefore,when the effects of metal cations on the hemolysis of jellyfish venoms are tested,a calibration analysis should be carried out.