Perturbation of Akt Signaling, Mitochondrial Potential, and ADP/ATP Ratio in Acidosis‐Challenged Rat Cortical Astrocytes

Abstract

Cells switch to anaerobic glycolysis when there is a lack of oxygen during brain ischemia. Extracellular pH thus drops and such acidosis causes neuronal cell death. The fate of astrocytes, mechanical, and functional partners of neurons, in acidosis is less studied. In this report, we investigated the signaling in acidosis-challenged rat cortical astrocytes and whether these signals were related to mitochondrial dysfunction and cell death. Exposure to acidic pH (6.8, 6.0) caused Ca release and influx, p38 MAPK activation, and Akt inhibition. Mitochondrial membrane potential was hyperpolarized after astrocytes were exposed to acidic pH as soon as 1 h and lasted for 24 h. Such mitochondrial hyperpolarization was prevented by SC79 (an Akt activator) but not by SB203580 (a p38 inhibitor) nor by cytosolic Ca chelation by BAPTA, suggesting that only the perturbation in Akt signaling was causally related to mitochondrial hyperpolarization. SC79, SB203580, and BAPTA did not prevent acidic pH-induced cell death. Acidic pH suppressed ROS production, thus ruling out the role of ROS in cytotoxicity. Interestingly, pH 6.8 caused an increase in ADP/ATP ratio and apoptosis; pH 6.0 caused a further increase in ADP/ATP ratio and necrosis. Therefore, astrocyte cell death in acidosis did not result from mitochondrial potential collapse; in case of acidosis at pH 6.0, necrosis might partly result from mitochondrial hyperpolarization and subsequent suppressed ATP production. J. Cell. Biochem. 118: 1108-1117, 2017. © 2016 Wiley Periodicals, Inc.

Dexmedetomidine alleviated neuropathic pain in dorsal root ganglion neurons by inhibition of anaerobic glycolysis activity and enhancement of ROS tolerance

“…Therefore, the main indicators of anaerobic glycolysis include glucose consumption, lactic acid and pyruvic acid production and ATP/ADP ratio. These are the markers used in studies of cell anaerobic glycolysis [45,46]. In our study, we found that dexmedetomidine significantly reduced H 2 O 2 -induced glucose consumption, pyruvic acid and lactic acid expression as well as increased the ATP/ADP ratio, in rat DRG neurons.…”

Efficaciousness of Low Affinity Compared to High Affinity TSPO Ligands in the Inhibition of Hypoxic Mitochondrial Cellular Damage Induced by Cobalt Chloride in Human Lung H1299 Cells

“…White 96-well plates were used to measure the levels of ADP and ATP. After pretreatment of cells in medium with and without CB86 and CB204, followed by CoCl 2 exposure, the ADP/ATP ratio was measured and calculated, according to the manufacturer's protocol (MAK135; Sigma-Aldrich, St. Louis, MO, USA), as previously described [46]. Luminescence levels of the ratio between ADP and ATP were measured by ELISA using Infinite M200 Pro plate reader (Tecan, Männedorf, Switzerland), according to the instructions of the manufacturer.…”

Do we have to consider acidosis induced by exercise as deleterious in sickle cell disease?

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