Functional response of the isolated, perfused normoxic heart to pyruvate dehydrogenase activation by dichloroacetate and pyruvate

Abstract

Dichloroacetate (DCA) and pyruvate activate pyruvate dehydrogenase (PDH), a key enzyme that modulates glucose oxidation and mitochondrial NADH production. Both compounds improve recovery after ischemia in isolated hearts. However, the action of DCA and pyruvate in normoxic myocardium is incompletely understood. We measured the effect of DCA and pyruvate on contraction, mitochondrial redox state, and intracellular calcium cycling in isolated rat hearts during normoxic perfusion. Normalized epicardial NADH fluorescence (nNADH) and left ventricular developed pressure (LVDP) were measured before and after administering DCA (5 mM) or pyruvate (5 mM). Optical mapping of Rhod-2AM was used to measure cytosolic calcium kinetics. DCA maximally activated PDH, increasing the ratio of active to total PDH from 0.48±0.03 to 1.03 ±0.03. Pyruvate sub-maximally activated PDH to a ratio of 0.75±0.02. DCA and pyruvate increased LVDP. When glucose was the only exogenous fuel, pyruvate increased nNADH by 21.4±2.9 % while DCA reduced nNADH by 21.4±6.1 % and elevated the incidence of premature ventricular contractions (PVCs). When lactate, pyruvate, and glucose were provided together as exogenous fuels, nNADH increased with DCA, indicating that PDH activation with glucose as the only exogenous fuel depletes PDH substrate. Calcium transient time-to-peak was shortened by DCA and pyruvate and SR calcium re-uptake was 30 % longer. DCA and pyruvate increased SR calcium load in myocyte monolayers. Overall, during normoxia when glucose is the only exogenous fuel, DCA elevates SR calcium, increases LVDP and contractility, and diminishes mitochondrial NADH. Administering DCA with plasma levels of lactate and pyruvate mitigates the drop in mitochondrial NADH and prevents PVCs.

Recombinant ostreolysin induces brown fat-like phenotype in HIB-1B cells

“…The levels of most of the examined genes were increased after 48 h of treatment and some were upregulated only following 72 h of treatment. Interestingly, Bmal1 level was downregulated after treatment with rOly, consistent with the data presented by Nam et al (33) who demonstrated inhibition of this gene during brown adipocyte differentiation.…”

(-)-Hydroxycitric Acid Reduced Lipid Droplets Accumulation Via Decreasing Acetyl-Coa Supply and Accelerating Energy Metabolism in Cultured Primary Chicken Hepatocytes

“…The pyruvate dehydrogenase complex converts pyruvate into acetyl-CoA, which may then be used in the citric acid cycle for cellular respiration [77]. The reaction catalyzed by pyruvate dehydrogenase (E1) is considered to be the rate-limiting reaction in the pyruvate dehydrogenase complex [77, 78]. The present results showed that (-)-HCA treatment significantly increased PDH (E1) protein content in primary chicken hepatocytes.…”

Lights, Camera, Path Splitter: A New Approach for Truly Simultaneous Dual Optical Mapping of the Heart with a Single Camera

“…Animals were anesthetized with 3-5% isoflurane, the heart was excised and then transferred to a temperature-controlled (37°C) constant-pressure (70 mmHg) Langendorff perfusion system. Excised hearts were perfused with Krebs-Henseleit buffer throughout the duration of the experiment, as previously described (<1 hour)(12,49,50). Three electrodes were positioned to acquire a far-field electrocardiogram in the lead II configuration.…”

“…Fluorescent dyes were added sequentially, as a bolus, through a bubble trap located proximal to the aortic cannula. Based on predetermined myocardial staining time for each dye, 50 μg Rhod-2AM(1,49) was added first and allowed to stabilize for 10 min, followed by 62.1 μg RH-237 staining for 1 min(12). The myocardial tissue was re-stained by RH237 if needed throughout the duration of the experiment(53).…”