The effect of DS16570511, a new inhibitor of mitochondrial calcium uniporter, on calcium homeostasis, metabolism, and functional state of cultured cortical neurons and isolated brain mitochondria.

Background: Disorders of mitochondrial Ca homeostasis play a key role in the glutamate excitotoxicity of brain neurons. DS16570511 (DS) is a new penetrating inhibitor of mitochondrial Ca uniporter complex (MCUC). The paper examines the effects of DS on the cultivated cortical neurons and isolated mitochondria of the rat brain.

Methods: The functions of neurons and mitochondria were examined using fluorescence microscopy, XF24 microplate-based сell respirometry, ion-selective microelectrodes, spectrophotometry, and polarographic technique.

Results: At the doses of 30 and 45 μM, DS reliably slowed down the onset of glutamate-induced delayed calcium deregulation of neurons and suppressed their death. 30 μM DS caused hyperpolarization of mitochondria of resting neurons, and 45 μM DS temporarily depolarized neuronal mitochondria. It was also demonstrated that 30-60 μM DS stimulated cellular respiration. DS was shown to suppress Ca uptake by isolated brain mitochondria. In addition, DS inhibited ADP-stimulated mitochondrial respiration and ADP-induced decrease in the mitochondrial membrane potential. It was found that DS inhibited the activity of complex II of the respiratory chain. In the presence of Ca, high DS concentrations caused a collapse of the mitochondrial membrane potential.

Conclusions: The data obtained indicate that, in addition to the inhibition of MCUC, DS affects the main energy-transducing functions of mitochondria.

General Significance: The using DS as a tool for studying MCUC and its functional role in neuronal cells should be done with care, bearing in mind multiple effects of DS, a proper evaluation of which would require multivariate analysis.