Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Polwarth Building, Foresterhill, Aberdeen AB25 2ZD, UK.
Comprehensive Heart Failure Center (CHFC), Würzburg, Deutsches Zentrum für Herzinsuffizienz Würzburg, Universitätsklinikum Würzburg, Am Schwarzenberg 15, Haus A15, 97078 Würzburg, Germany.
Cardiovasc Res. 2022 Jun 29;118(8):1932-1946. doi: 10.1093/cvr/cvab081.
Cardiac energetic impairment is a major finding in takotsubo patients. We investigate specific metabolic adaptations to direct future therapies.
An isoprenaline-injection female rat model (vs. sham) was studied at Day 3; recovery assessed at Day 7. Substrate uptake, metabolism, inflammation, and remodelling were investigated by 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography, metabolomics, quantitative PCR, and western blot (WB). Isolated cardiomyocytes were patch-clamped during stress protocols for redox states of NAD(P)H/FAD or [Ca2+]c, [Ca2+]m, and sarcomere length. Mitochondrial respiration was assessed by seahorse/Clark electrode (glycolytic and β-oxidation substrates). Cardiac 18F-FDG metabolic rate was increased in takotsubo (P = 0.006), as was the expression of GLUT4-RNA/GLUT1/HK2-RNA and HK activity (all P < 0.05), with concomitant accumulation of glucose- and fructose-6-phosphates (P > 0.0001). Both lactate and pyruvate were lower (P < 0.05) despite increases in LDH-RNA and PDH (P < 0.05 both). β-Oxidation enzymes CPT1b-RNA and 3-ketoacyl-CoA thiolase were increased (P < 0.01) but malonyl-CoA (CPT-1 regulator) was upregulated (P = 0.01) with decreased fatty acids and acyl-carnitines levels (P = 0.0001-0.02). Krebs cycle intermediates α-ketoglutarate and succinyl-carnitine were reduced (P < 0.05) as was cellular ATP reporter dihydroorotate (P = 0.003). Mitochondrial Ca2+ uptake during high workload was impaired on Day 3 (P < 0.0001), inducing the oxidation of NAD(P)H and FAD (P = 0.03) but resolved by Day 7. There were no differences in mitochondrial respiratory function, sarcomere shortening, or [Ca2+] transients of isolated cardiomyocytes, implying preserved integrity of both mitochondria and cardiomyocyte. Inflammation and remodelling were upregulated-increased CD68-RNA, collagen RNA/protein, and skeletal actin RNA (all P < 0.05).
Dysregulation of glucose and lipid metabolic pathways with decreases in final glycolytic and β-oxidation metabolites and reduced availability of Krebs intermediates characterizes takotsubo myocardium. The energetic deficit accompanies defective Ca2+ handling, inflammation, and upregulation of remodelling pathways, with the preservation of sarcomeric and mitochondrial integrity.
心肌能量损伤是应激性心肌病患者的主要发现。我们研究了特定的代谢适应，以指导未来的治疗。
对雌性大鼠进行异丙肾上腺素注射（应激组），并设立假手术组（对照），于第 3 天进行研究，第 7 天进行恢复评估。通过 18F-氟脱氧葡萄糖（18F-FDG）正电子发射断层扫描、代谢组学、定量 PCR 和 Western blot（WB）检测底物摄取、代谢、炎症和重构。在应激方案下，对分离的心肌细胞进行还原型烟酰胺腺嘌呤二核苷酸（NAD（P）H）/黄素腺嘌呤二核苷酸（FAD）或[Ca2+]c、[Ca2+]m 和肌节长度的氧化还原状态进行膜片钳检测。通过 Seahorse/Clark 电极（糖酵解和β-氧化底物）评估线粒体呼吸。应激性心肌病大鼠的心肌 18F-FDG 代谢率增加（P=0.006），葡萄糖转运蛋白 4-RNA/葡萄糖转运蛋白 1/己糖激酶 2-RNA 和己糖激酶活性增加（均 P<0.05），同时伴有葡萄糖-6-磷酸和果糖-6-磷酸的积累（均 P>0.0001）。尽管乳酸脱氢酶 RNA 和丙酮酸脱氢酶增加（均 P<0.05），但乳酸和丙酮酸均降低（均 P<0.05）。β-氧化酶肉碱脂酰转移酶 1b-RNA 和 3-酮酰基辅酶 A 硫解酶增加（均 P<0.01），但丙二酰辅酶 A（CPT-1 调节物）上调（P=0.01），脂肪酸和酰基辅酶 A 水平降低（均 P=0.0001-0.02）。三羧酸循环中间产物α-酮戊二酸和琥珀酰肉碱减少（均 P<0.05），细胞 ATP 报告二氢乳清酸减少（P=0.003）。第 3 天，高工作负荷下的心肌细胞 Ca2+摄取受损（P<0.0001），导致 NAD（P）H 和 FAD 氧化（P=0.03），但在第 7 天恢复。分离的心肌细胞线粒体呼吸功能、肌节缩短或 Ca2+瞬变无差异，提示线粒体和心肌细胞完整性得以保留。炎症和重构上调-增加 CD68-RNA、胶原 RNA/蛋白和骨骼肌肌动蛋白 RNA（均 P<0.05）。
应激性心肌病心肌中葡萄糖和脂质代谢途径失调，最终糖酵解和β-氧化代谢产物减少，三羧酸循环中间产物减少，提示能量不足。这种能量缺陷伴随着 Ca2+处理缺陷、炎症和重构途径的上调，以及肌节和线粒体完整性的保留。
