Figure 1.
Dynasore is a specific small molecular GTPase inhibitor that targets Dynamin1 and Dynamin2 which are responsible for pinching off endocytic vesicles, and Drp1 which is responsible for mitochondrial fission.
Figure 2.
The cardiac lusitropic effect of Dynasore.
Effect of 1 µM Dynasore pretreatment on ventricular function was studied in Langendorff perfused mouse hearts subjected to 30 min no-flow global ischemia followed by 60 min reperfusion. Hearts were paced at 360 bpm during the whole experimental protocol except the ischemia period and pacing was reinitiated at 2 min into the reperfusion period. A. Representative Left ventricular pressure tracing in a control heart and a Dynasore treated heart. B, C; Left ventricular end diastolic pressure (LVEDP, B) and left ventricular developed pressure (LVDP, C) are summarized and compared between control group and Dynasore group. (* P<0.05).
Table 1.
Effect of 1 µM Dynasore pretreatment on ventricular function in Langendorff perfused mouse hearts during ischemia/reperfusion injury.
Figure 3.
Dynasore decreases cardiomyocyte death in I/R injured mouse hearts.
A. Myocardial infarct size was analyzed by Propidium Iodide (PI) perfusion. Left, representative fluorescence images of PI staining in a control and Dynasore treated hearts subjected to I/R injury. Right, average infarct size is presented as percentage over total left ventricular area and compared between the two treatment groups. B. Dynasore decreases cardiac troponin I (cTnI) efflux. Myocardial damage was evaluated by measurement of the release of cTnI in the coronary effluent during the 60 min reperfusion period. (* P<0.05, ***P<0.001).
Figure 4.
Dynasore increasses cardiomyocyte survival and viability.
Trypan blue exclusion assay was used to identify cell survival and viability of cardiomyocytes subjected to oxidative stress in the presence (A) and absence of FBS (B). A. Dynasore increases cell survival and viability in oxidative stressed (exposed to 30µM H2O2 for 35 min) cardiomyocytes. Top, representative phase images of cardiomyocytes. Bottom, summarized cell survival and viability results. B. Dynasore further increased cell survival and viability in serum depleted and oxidative cardiomyocytes. Top, representative phase images of cardiomyocytes. Bottom, summarized cell survival and viability results. (** P<0.01, ***P<0.001 when compared to stressed cardiomyocytes without Dynasore treatment; † P<0.05, ††† P<0.001 when compared to non-stressed cardiomyocyte controls).
Figure 5.
Dynasore preserves cellular ATP content in stressed cardiomyocytes.
A. Dynasore preserves cardiomyocyte ATP content. Adult mouse cardiomyocytes were exposed to 30µM H2O2 for 35 min in the absence and presence of Dynasore. Cellular ATP content (total ATP normalized to amount of surviving cardiomyocytes) were calculated and compared among the different treatment groups. B. Direct supplement of ATP (3 mM in culture medium) increases cardiomyocyte survival after H2O2 exposure. (**P<0.01, ***P<0.001 when compared to H2O2 stressed cardiomyocytes without Dynasore treatment; †P<0.05, †††P<0.001 when compared to control cardiomyocytes).
Figure 6.
Effects of Dynasore on cellular ATP content in unstressed Hela cells.
Low dose Dynasore does not change cellular ATP content in unstressed Hela cells, whereas high dose of Dynasore (>10 µM) increases ATP content. Cellular ATP content were calculated and compared among the different treatment groups. (*P<0.05, **P<0.01 when compared to control cells without Dynasore treatment).
Figure 7.
Dynasore prevents oxidative stress-induced mitochondrial fission.
Cultured human Hela cells were used for mitochondrial morphology study. Top, Hela cells have elongated connected mitochondrial network (left), which was fragmented after oxidative stress (right). Bottom, 1 µM Dynasore pretreatment prevents oxidative stress-induced mitochondrial fragmentation.