Heart damage in diabetics may be closely related to the possible synergistic cellular damage from hyperglycemia and increased methylglyoxal levels. This study investigated the effects of glucose and/or methylglyoxal and/or metformin on H9c2 reactive oxygen species (ROS) generation measured by a dichlorofluorescein diacetate (DCFDA) assay and cell viability measured by a cell counting kit-8 assay after various treatments for 24 hours.
Glucose treatment (5 mM-40 mM) displayed similar cell viability (n=4) and ROS generation (n=7) when compared to control cells. By contrast, methylglyoxal (5 µM-1400 µM) decreased cell viability at higher concentration (1000 µM (51 ± 8%); 1200 µM (41 ± 5%); 1400 µM (36 ± 8%); all p\u3c0.05, n=5) compared to control cells, which was accompanied by significantly higher ROS generation (1000 µM (167 ± 27%); 1200 µM (204 ± 22%); 1400 µM (201 ± 15%); all p\u3c0.05, n=3). Furthermore, metformin (1 mM-40 mM) reduced methylglyoxal (1200 µM) induced ROS generation and cell death.
When H9c2 cells were treated with glucose (25 mM or 40 mM) and different doses of methylglyoxal (600 µM -1400 µM), only higher glucose (40 mM) with different doses of methylglyoxal (600 µM -1400 µM) consistently showed lower cell viability and higher ROS when compared to individual glucose or methylglyoxal.
The data suggest that higher concentrations of methylglyoxal, not glucose, induces H9c2 cell damage and metformin can protect cells from the methylglyoxal insult possibly by reduction of ROS production. Moreover, hyperglycemia and methylglyoxal tend to synergistically induce cell damage associated with increased ROS production
