Obesity and type 2 diabetic (T2D) cause cardiac dysfunction, which could be related to chronically activated sympathoadrenergic system (SAS). SAS system activation leads to the activation of PKA in cardiomyocytes. In this study, we aimed to test the hypothesis that chronically activated PKA plays an important role in obese induced cardiac dysfunction.
Methods and Results: 1. Cardiomyocyte specific PKA inhibition (cPKAi) transgenic (TG) mouse model (n=18) and nontransgenic littermate control (NLC, n=20) mice (3-month old) were fed with high fat food (D12451, Research Diet) or normal chow for 6 months.2. In 3-month old male TG mice, intraperitoneal glucose injection did not increase blood glucose as high as in 3-month old NLC mice. The area under the curve of cPKAi TG mice was significantly less than that of control mice. cPKAi transgenic mice had decreased cardiac function after overnight fasting while control mice did not have cardiac function decrement even though both types of mice had the same extend of glucose reduction after overnight fasting. 3. The BW increase was more in TG mice. 4. After HFD feeding, cPKAi TG group had better cardiac function: (1). The maximal systolic pressure (mmHg) of TG (107.8±4.49) was significantly higher than that of NLC (83.0±8.1) mice. (2). The end diastolic pressure (EDP, mmHg) of TG (2.7 ± 2.2) was significantly lower in TG mice (11.5 ± 3.3); (3). Maximum dp/dt was significantly greater in TG than in NLC mice; (4). The relaxation rate of the heart was significantly better in TG than in NLC mice; 5. The HW/BW (mg/g) was significantly less in TG mice (4.6 ± 0.2) than in control mice (5.2 ± 0.2). 6. HFD reduced myocytes contractions, Ca transients, and Ca currents in both groups but the reduction was less in TG myocytes. 7. TG hearts had less inflammatory cell infiltration and fibrosis than control hearts.
Conclusion: cPKAi enhances cardiac glucose uptake and ameliorates cardiac remodeling and preserves cardiac function in HFD-induced obese.
X. Chen: None.
American Diabetes Association (1-19-IBS-210)