Cardiorespiratory alterations in rodents experimentally envenomed with Hadruroides lunatus scorpion venom

Abstract Background Hadruroides lunatus is the most abundant scorpion species in the Peruvian central coast, where most of the accidents involving humans are registered. In spite of its prevalence, there are only very few studies on H. lunatus envenomation. The aim of the present study was to analyze the cardiorespiratory alterations caused by H. lunatus envenomation in rodents. Methods Wistar rats injected with H. lunatus scorpion venom were submitted to electrocardiography. After euthanasia, rat lungs were collected and histopathologically analyzed. Mouse cardiomyocytes were used to perform immunofluorescence and calcium transient assays. Data were analyzed by ANOVA or Student’s t-test. The significance level was set at p< 0.05. Results It was observed that H. lunatus venom increased heart rate and caused arrhythmia, thereby impairing the heart functioning. Lungs of envenomed animals showed significant alterations, such as diffuse hemorrhage. In addition, immunofluorescence showed that H. lunatus venom was capable of binding to cardiomyocytes. Furthermore, mouse ventricular cardiomyocytes incubated with H. lunatus venom showed a significant decrease in calcium transient, confirming that H. lunatus venom exerts a toxic effect on heart. Conclusion Our results showed that H. lunatus venom is capable of inducing cardiorespiratory alterations, a typical systemic effect of scorpionism, stressing the importance of medical monitoring in envenomation cases.

Effects of site specific antibody of Na+-Ca2+exchanger on calcium transient in single ventricular myocytes of rats / 中国免疫学杂志

Objective:To investigate the effects of site specific (124 HNFTAGDLGP STIVGSAAFNMF145 ) antibody of Sodium calcium exchanger ( NCX) on calcium transient in single ventricular myocytes of normal adult rats .Methods: Isolated adult rat hearts were perfused using Langendorff method and single ventricular myocytes were then obtained .The ventricular myocytes were incubated with Fuar-2/AM and 2% bovine serum albumin for about 40 min and then,the fluorescence images were recorded when excitation wavelengths were 340 nm and 380 nm using ion imaging system.Fluorescence value F340/F380,length of cell shortening ,time to 90%restore( TR90 ) and calcium sensitivity ( ratio of F340/F380 and cell shortening ) were calculated.Results:The site specific antibody of NCX increased F340/F380 and decreased TR90 in single ventricular myocytes ,but had no more significant effect on calcium sensitivi-ty.Pretreatment with KB-R7943 or Nicardipine could significantly inhibit the TR 90 decrease or F340/F380 increase induced by the anti-body.Pretreating ventricular myocytes with combination of KB-R7943 and Nicardipine ,the antibody had no more significant effects on calcium transient.Conclusion:Site specific ( 124 HNFTAGDLGPSTIVGSAAFNMF145 ) antibody of NCX could increase calcium transient and accelerate the decrease of intracellular calcium during diastole ,which mainly related to its effects of activating L-type Ca2+channel and NCX.

Cardiorespiratory alterations in rodents experimentally envenomed with Hadruroides lunatus scorpion venom

Abstract Background Hadruroides lunatus is the most abundant scorpion species in the Peruvian central coast, where most of the accidents involving humans are registered. In spite of its prevalence, there are only very few studies on H. lunatus envenomation. The aim of the present study was to analyze the cardiorespiratory alterations caused by H. lunatus envenomation in rodents. Methods Wistar rats injected with H. lunatus scorpion venom were submitted to electrocardiography. After euthanasia, rat lungs were collected and histopathologically analyzed. Mouse cardiomyocytes were used to perform immunofluorescence and calcium transient assays. Data were analyzed by ANOVA or Students t-test. The significance level was set at p 0.05. Results It was observed that H. lunatus venom increased heart rate and caused arrhythmia, thereby impairing the heart functioning. Lungs of envenomed animals showed significant alterations, such as diffuse hemorrhage. In addition, immunofluorescence showed that H. lunatus venom was capable of binding to cardiomyocytes. Furthermore, mouse ventricular cardiomyocytes incubated with H. lunatus venom showed a significant decrease in calcium transient, confirming that H. lunatus venom exerts a toxic effect on heart. Conclusion Our results showed that H. lunatus venom is capable of inducing cardiorespiratory alterations, a typical systemic effect of scorpionism, stressing the importance of medical monitoring in envenomation cases.

Effects of aralosdie C on excitation-contraction coupling of ischemia / reperfusion cardiomyocytes and role of CaMK II regulation / 中国药理学通报

Aim To investigate the effects of aralosdie C (SMC)isolated from aralosides on contractile func-tion and calcium transients in ischemia / reperfusion(I/R)-induced rat myocardial injury and the role of CaMK II. Methods The cardiomyocytes were divided into control group,I/ R group,I/ R + SMC group,KN-93+ I/ R + SMC group. The effect of SMC on the con-tractile function and calcium transient of I/ R cells was measured by cell shrinkage and ion concentration sim-ultaneous detection system. Results SMC(8 μmol· L - 1 )improved the contractile function of I/ R cardio-myocytes and the calcium transients,and SMC in-creased the rate of calcium transient and [Ca2 +]i up /down regulation significantly. While CaMK II was blocked by KN-93,the effect of SMC on contractile function and calcium transients was weakened. Con-clusions SMC can significantly improve the systolic function and calcium transients of cardiomyocytes in I/R rats,and the protective effect of SMC on cardiomyo-cytes may be related to CaMK II.

Homocysteine, Hydrogen sulfide (H2S) and NMDA-Receptor in Heart Failure.

Mitochondrial mechanism of oxidative stress and matrix metalloproteinase (MMP) activation was unclear. Our recent data suggested that MMPs are localized to mitochondria and activated by peroxynitrite, which causes cardiovascular remodeling and failure. Recently, we have demonstrated that elevated levels of homocysteine (Hcy), known as hyperhomocysteinemia (HHcy) increase oxidative stress in the mitochondria. Although HHcy causes heart failure, interestingly, it is becoming very clear that Hcy can generate hydrogen sulfide (H2S), if the enzymes cystathionine β-synthase (CBS) and cystathionine -lyase (CGL) are present. H2S is a strong anti-oxidant and vasorelaxing agent. Paradoxically, it is interesting that Hcy, a precursor of H2S can be cardioprotective. The CGL is ubiquitous, while the CBS is not present in the vascular tissues. Therefore, under normal condition, only half of Hcy can be converted to H2S. However, there is strong potential for gene therapy of CBS to vascular tissue that can mitigate the detrimental effects of Hcy by converting it to H2S. This scenario is possible, if the activities of both the enzymes (CBS and CGL) are increased in tissues by gene therapy.

Effect of Total Flavonoids of Hippophae Rhamnoides on Contractile Mechanics and Calcium Transfer in Stretched Myocyte / 航天医学与医学工程

Objective To study the role of total flavonoids of hippophae rhamnoides in improving contactile function of stretched cardiac myocyte.Method Flavonoids were given to stretched myocytes which were proved their contractile function decline and then myocyte contractile mechanics characteristics and calcium transfer were measured.Result Flavonoids increased myocyte contractility,as indicated by myocyte shortening,velocity of shortening,peak+dL/dt and peak-dL/dt during shortening,in a concentration-dependent manner (r>0.9,P<0.001),and with no relation to the intracellular calcium transfer in the myocytes.Conclusion Flavonoids of the traditional Chinese drug hippophae rhamnoids is effective in improving the contractile function of stretched cardiac myocyte in low dosage.

Effects of bradykinin on intracellular calcium transients in cardiac myocytes

In spite many evidences has supported the cardioprotective effect of bradykinin, its direct effects at the cell level are still under question. We investigated the both effects of bradykinin (BK) on Ca2+-related ionic currents using whole cell voltage clamp technique in rabbit cardiomyocytes and on the intracellular Ca2+ transient using calcium sensitive fluorescence dye, indo-1AM. Simultaneously with recording intracellular Ca2+ transients, cell contractility was estimated from the changes in length of the electrical stimulated rat cardiac myocytes. L-type Ca2+ current decreased by bradykinin at the entire voltage range. Inward tail current increased initially up to its maximum about 4 min after exposing myocytes to BK, and then gradually decreased again by further exposure to BK. This tail current decreased remarkably at washing BK off but slowly recovered ca. 20 min later. The change in cell contractility was similar to that in tail current showing initial increase followed by gradual decrease. Removal of BK brought remarkable decrease in contractility, which was recovered 15~20 min after cessation of electrical stimulation. Bradykinin increased Ca2+ transient initially but after some time Ca2+ transient also decreased coincidentally with contractility. From these results, it is suggested that bradykinin exerts directly its cardioprotective effect on the single myocytes by decreasing the intracellular Ca2+ level followed by an initial increase in Ca2+ transient.

Effects of chronic heart failure on contractile/diastolic function and calcium transient in guinea pig ventricular myocytes detected simultaneously by video-based motion edge-detection system / 中国药理学通报

Aim To develop the animal model of guinea pig chronic heart failure and detect effects of chronic heart failure on contractile/diastolic function and calcium transient in guinea pig ventricular myocytes by video-based motion edge-detection system simultaneously.Methods The chronic congestive heart failure(CHF) model was produced in guinea pig by a procedure that descenting aorta was constricted.The contrasting indexes in 8 weeks include: with or without dyspnea,hemodynamics,the mass ratio of left ventricle to body,the mass ratio of lung to body,and the width of left ventricle.Left ventricular myocytes were enzymatically isolated.Then the contractile and calcium transient of a single cell from both normal and failure hearts were assessed in guinea pigs by a video-based motion edge-detection system simultaneously.Results The models with dyspnea showed striking increasing in left ventricular systolic pressure and left ventricular end diastolic pressure,as well as the mass ratio of left ventricle to body,the mass ratio of lung to body and the width of left ventricular hypertrophy.The left ventricular pressure maximal rising and declining velocity significantly decreased.Compared with normal cells,the value of shorting,the contractile and diastolic velocity of myocytes decreased significantly.The diastolic calcium increased,the extent of calcium transient[FL(2K2] decreased and the time to 50% diastolic calcium lengthen.But systolic calcium,the time to peak calcium were unchanged.Conclusions The dyspnea is a important parameter for evaluating the animal CHF model of guinea pig formed by constricting the descending aortas of guinea pigs after 8 weeks.The chronic heart failure may decrease contractile and calcium transient extent in ventricular myocytes detected by video-based motion edge-detection system simultaneously,which might be helpful for the further studying the mechanism of the development of CHF.

Effects of renovascular hypertension on contractile/ diastolic function,calcium transient and calcium sensitivity in rat ventricular myocytes / 中国药理学通报

Aim To observe effects of hypertension on contractile/diastolic function and calcium transient in rats ventricular myocytes. Methods The model of one-kidney-one-clip (1k1c) hypertensive rat was pre-pared by partially ligating the left renal artery and removing the right kidney. Left ventricular myocytes were enzymatically isolated. Then the contraction and calcium transient of a single cell from both normal and renovascular hypertensive rats were observed by a video-based motion edge-detection system simultaneously. Effects of calcium in various concentrations on contractile/diastolic function and calcium transient in ventricular myocytes from renovascular hypertensive rats were assessed in the same way. Results Compared with normal cardiac myocytes, the shorting amplitude and the contractile and diastolic velocity were increased significantly in 1k1c hypertensive rat cardiac myocytes. However their intracellular calcium in contractile and diastolic periods, the extent of calcium transient and the parameters of intracellular calcium dynamics were unchanged. But the extracellular calcium of different concentrations could shift the Fura-2 fluorescence ratio-cell shorting amplitude curve from hypertension rat myocytes to the left compared with that from normal rats. Conclusions The hypertension increases the contractility of rat cardiac myocytes, which is due to raising their sensitivity to calcium.