Carbon monoxide shifts energetic metabolism from glycolysis to oxidative phosphorylation in endothelial cells

Abstract

Carbon monoxide (CO) modulates mitochondrial respiration, but the mechanisms involved are not completely understood. The aim of the present study was to investigate the acute effects of CO on bioenergetics and metabolism in intact EA.hy926 endothelial cells using live cell imaging techniques. Our findings indicate that CORM-401, a compound that liberates CO, reduces ATP production from glycolysis, and induces a mild mitochondrial depolarization. In addition, CO from CORM-401 increases mitochondrial calcium and activates complexes I and II. The subsequent increase in mitochondrial respiration leads to ATP production through oxidative phosphorylation. Thus, our results show that nonactivated endothelial cells rely primarily on glycolysis, but in the presence of CO, mitochondrial Ca increases and activates respiration that shifts the metabolism of endothelial cells from glycolysis- to oxidative phosphorylation-dependent ATP production.

CORM‐401 induces calcium signalling, NO increase and activation of pentose phosphate pathway in endothelial cells

“…A) seem to also be important to restore a reduced pool of GSH via glutathione reductase, which converts GSSG to GSH to maintain intercellular stores of reduced glutathione (GSH), essential to neutralize ROS. Previously we did not observe in endothelial cells increased ROS production in response to CO , but it did not mean that they were not produced. It might as well be that ROS were not detected or underwent rapid neutralization.…”

“…We demonstrate here that inhibition of NO production by l ‐NAME or inhibition of superoxide production by poly(ethylene glycol)‐SOD completely blocked CO‐induced calcium signalling, suggesting the involvement of peroxynitrite. Interestingly, we demonstrated previously that CORM‐401 did not increase superoxide generation in EA.hy926 cells , implicating that increased NO and basal superoxide were involved in RyR activation. This could stay in line with the results showing NO‐triggered Ca 2+ ions release from ER in rat hippocampal neurons, mediated by both IP3R1 and RyR, which required physiological ROS levels only .…”

“…It was reported that NO activates RyR indirectly, via formation of peroxynitrite from NO interacting with superoxide anion . Although the application of CORM‐401 to EA.hy926 cells did not seem to increase basal superoxide production , a treatment with superoxide dismutase (30 min preincubation with 100 U·mL −1 poly(ethylene glycol)‐SOD) completely blocked CO‐induced [Ca 2+ ] c signals (Fig. B).…”

“…). On the other side, we demonstrated previously that CO uncouples mitochondria and reduces mitochondrial membrane potential in EA.hy926 cells, what can play a protective role against oxidative stress. Moreover, in the present work we observe a decreased ratio of reduced to oxidized glutathione (GSH/GSSG) following CO exposure (Fig.…”

Biological signaling by carbon monoxide and carbon monoxide-releasing molecules

“…Interestingly, mitochondrial BK Ca channels appear to mediate this effect in endothelial cells (47) but not in microglia cells, suggesting that multiple mechanisms are involved. In addition, this interaction of low CO levels with mitochondria affects metabolism, since treatment of endothelial cells with CO results in a shift from glycolysis to oxidative phosphorylation (46). Almeida et al (2) have also shown in astrocytes that exposure to CO increased ATP generation and O 2 consumption with a general improvement in oxidative phosphorylation.…”