Intracellular Calcium Changes Correlate with Mitochondrial Dynamics After Differential Modulation of KATP Channels in a Cellular Model of Parkinson's Disease.

Up-to-date data on roles of ATP‑sensitive potassium (KATP) channels indicate their emerging roles in neurodegeneration. The aim of present study was to evaluate the significance of KATP channels on cell viability, calcium dynamics, and mitochondrial morphology with the accent on their intracellular localization. We distinguished between whole-cell KATP effects and specific effects of mitochondrial KATP under both physiological conditions and pathological conditions simulating in vitro Parkinson´s-type neurodegeneration. SH‑SY5Y cells with its high fidelity to dopaminergic neurons were treated for 24 h with the non‑selective KATP opener pinacidil and blocker glibenclamide, or with the mitochondrial KATP opener diazoxide and blocker 5‑hydroxydecanoate (5HD). The effects of modulators were analysed alone or alongside with rotenone, which is widely used as an inducer of Parkinson´s-type neurodegeneration. Intracellular calcium distribution and mitochondrial rebuild pattern was evaluated using the cell segmentation performed by fluorescent confocal microscopy. Although none of the KATP modulators reversed the negative effects of rotenone, significant and selective effects of mitochondrial KATP modulation on calcium homeostasis and mitochondrial morphology were observed. For antagonists, both compounds showed consistent effects, with non-selective glibenclamide exerting stronger effects, particularly in elevating calcium. More distinctive results were obtained for agonists: both reduced calcium concentration; however, pinacidil tended to induce mitochondrial fragmentation, an effect absent in diazoxide-treated cells. Furthermore, strong correlations were identified between calcium levels and several mitochondrial and cell viability parameters.