Reduction of intracellular Mg < sup > 2+ < /sup > caused by reactive oxygen species in rat ventricular myocytes

Am J Physiol Cell Physiol. 2023 Mar 13. doi: 10.1152/ajpcell.00490.2022. Online ahead of print.ABSTRACTThe concentration of intracellular free Mg2+ ([Mg2+]i) should be maintained strictly for the regulation of cellular functions. Since reactive oxygen species (ROS) are liable to increase in various pathological conditions and induce cellular damage, we investigated whether ROS affect intracellular Mg2+ homeostasis. We measured [Mg2+]i in ventricular myocytes from Wistar rats using the fluorescent indicator, mag-fura-2. The administration of hydrogen peroxide (H2O2) decreased [Mg2+]iinCa2+-free Tyrode's solution. Intracellular free Mg2+ was also reduced by endogenous ROS as generated by pyocyanin, which was inhibited by pretreatment with n-acetyl cysteine. The rate of change in [Mg2+]i by 500 μM H2O2 in 5 min (on average, -0.61 μM/s) was independent of extracellular Na+, and intra- and extracellular Mg2+ concentrations. When extracellular Ca2+ was present, the rate of Mg2+ decrease was significantly reduced, on average, by ~ 60%. The half maximal effective concentration of H2O2 on the Mg2+ decrease was estimated to be between 400 and 425 μM. The Mg2+ decrease by H2O2 in the absence of Na+ was inhibited by 200 μM imipramine, a known inhibitor of Na+/Mg2+ exchange. We perfused rat hearts with the Ca2+-free Tyrode's solution containing H2O2 (500 μM, 5 min) on the Langendorff apparatus. H2O2 stimulation increased Mg2+ concentration in the perfusate, suggesting the H2O2-induce...
Source: Am J Physiol Cell Ph... - Category: Cytology Authors: Source Type: research