Anne-Marie Koop

82 Figure 5 . Mitochondrial function. Plots of mitochondrial content measured by mentioned methods (A). Bubble plot showing relation between mitochondrial content and duration of RV pressure load (B). Forrest plot of PDH activity as reflection of mitochondrial breakdown of pyruvate to acetyl-CoA (C). Forrest plots of mitochondrial respiratory capacity for carbohydrate metabolites measured in isolated mitochondria (ADP-driven) (D-1) or intact cardiomyocytes (D-2). Forrest plots of MCAD expression at mRNA level (E), as representative of the β -oxidation. Forrest plots of mitochondrial respiratory capacity for fatty acids measured in isolated mitochondria (F-1) and intact cardiomyocytes (F-2). Data are presented as Hedges’ g. Combined Hedges’ g are presented as squares: grey representing Hedges’ g of a specific model, black representing Hedges’ g of all included studies. Bars represent 95% confidence interval. Bubble size represents relative study precision, calculation based on standard deviation. Grey bubbles are not included in meta-analysis. Black line represents regression line, grey lines represents 95% confidence interval. SuHx = Sugen hypoxia, PAB = pulmonary artery banding, MCT = monocrotaline, FHR = fawn hooded rats, CO = cardiac output, CI = cardiac index, TAPSE = tricuspid annular plane systolic movement, RVEF = RV ejection fraction, ↓ = decreased, ↓↓ = decreased compared to decompensated group, “=” = not statistically significant affected. 95% CI = 95% confidence interval, n = number of included animals, i² = level of heterogeneity, X = not included in meta-analysis. * = significantly (p < 0.05) increased compared to PAB. Glucose oxidation Activity of PDH, the enzyme converting pyruvate into acetyl-CoA in themitochondria, tended to be decreased in RV pressure load but did not reach statistically significance (g = -1.982, p = 0.123) 15,16,18,21 ( figure 5c ). A similar result was observed for PDK4, a negative regulator of PDH, (resp. g = -1.91, p = 0.110), where meta-analysis of expression at both mRNA 16,34,35 and protein level 16,17,32 was unchanged ( suppl. figure 2a,b ). The same was true for PDK1 and PDK2 at protein level 16,17,32 ( suppl. figure 2c,d ). Heterogeneity was not explained by the duration or degree of pressure load ( suppl. tables 2 and 3 ), or the different models. Respiratory capacity of glucose or pyruvate was reported in seven articles. Analysis was divided in ADP-driven respiratory state measured in isolated mitochondria with oxygraphy (Oroboros or Clark-type) (n=2) 20,29 ( figure 5d-1 ), and respiratory capacity measured in intact cardiomyocytes with Seahorse (n=2) 16,21 or isolated heart model (Langendorf) (n=3) 15,16,18 ( figure 5d-2 ). Subsequently, measurements in isolated mitochondria did not met the inclusion criteria for meta-analysis. Respiratory capacity measured by all methods showed a negative trend, albeit meta-analysis of respiratory capacity for carbohydrates in intact cardiomyocytes did not reveal a significant decrease (g = -1.21 p = 0.082). Respiratory capacity did increase in the MCT-model compared to PAB (p < 0.05) ( figure 5d ). Meta-regression analyses did not reveal correlations between respiratory capacity and duration or degree of RV pressure load.