PQQ protects against H₂O₂ in rat cardiac myocytes. Acutely isolated adult rat cardiac myocytes grown on laminin-coated glass coverslips were exposed to control (vehicle-treated), H₂O₂, or H₂O₂ + PQQ. Control – vehicle treatment; H₂O₂ (1 mM) for 10 min; PQQ (10 μM) pretreatment for at least 30 minutes prior to experiment.
(A) Acutely isolated rat cardiac myocytes treated with from vehicle (control), H₂O₂ (1 mM and 100 μM), ± bovine serum albumin (BSA).
(B) Rat cardiac myocytes incubated with 0.1% BSA were assayed for cell viability, and mean values (± SEM) from control, H₂O₂, and H₂O₂+PQQ experimental groups are represented. Approximately 400-600 cells were counted in a total of 10 fields per dish for each experimental group. Three rat hearts were used for each of the conditions shown in the bargraph.
(C) Representative images of acutely isolated rat cardiac myocytes from control, H₂O₂, and H₂O₂+PQQ experimental groups. Live cells were rod-shaped and excluded the vital dye trypan blue, indicating an intact plasma membrane. Dead cells were contracted and stained positive for trypan blue, indicating a compromised plasma membrane. ** p<0.01 compared to control.

Sample traces of ROS-mediated oxidation of CM-H2XRos plotted as an increase in fluorescence over time. H₂O₂ caused an increase in CM-H2XRos fluorescence (dotted line), which was dose-dependently reduced by increasing PQQ concentrations. PQQ alone (10 μM) did not cause any significant change in CM-H2XRos fluorescence (solid line, bottom trace).

PQQ protects against an increase in cellular reactive oxygen species (ROS) in acutely isolated adult rat cardiac myocytes.
(A) Rat cardiomyocytes were loaded with CM-H2XRos to detect the increase in intracellular levels of ROS. CM-H2XRos fluorescence was collected, and fluorescence (F) at the indicated timepoint was normalized to baseline fluorescence (F_o) and plotted over time. Bar indicates addition of H₂O₂. Each point represents the mean ± SEM of 3-5 coverslips, each prepared from a separate rat heart. For each coverslip, 1-3 cells were analyzed. Veh – vehicle treatment (control); H₂O₂ (1 mM); PQQ (10 μM); MnTBAP (10 μM); PQQ and MnTBAP were administered for at least 30 minutes prior to H₂O₂.
(B) Peak cellular levels of ROS detected as a function of CM-H2XRos normalized to baseline value after 60 min H₂O₂ exposure. PQQ (gray bars) and MnTBAP (black bars) significantly reduced fluorescence compared to control (white bars).
(C) Cardiomyocytes were loaded with DHE to detect the increase in intracellular levels of ROS. DHE fluorescence was collected, and fluorescence (F) at the indicated timepoint was normalized to baseline fluorescence (F_o) and plotted over time. Arrow indicates addition of H₂O₂. Each point represents the mean ± SEM of 3-5 coverslips, each derived from a separate rat heart. For each coverslip, 1-3 cells were analyzed. Veh – vehicle treatment (control); H₂O₂ (1 mM); MnTBAP (10 μM); PQQ and MnTBAP were administered for at least 30 minutes prior to H₂O₂.
(D) Peak cellular levels of ROS detected as a function of DHE normalized to baseline value after 40 min H₂O₂ exposure. PQQ (gray bars) and MnTBAP (black bars) significantly reduced fluorescence compared to control (white bars). ** p<0.01 compared to control (H₂O₂ alone).

PQQ protects against H₂O₂-mediated Δψ_m depolarization in acutely isolated adult rat cardiac myocytes.
(A) Rat cardiomyocytes were loaded with TMRM to quantify Δψ_m depolarization. TMRM fluorescence was collected, and fluorescence (F) at indicated timepoint was normalized to baseline fluorescence (F_o) and plotted over time. Bar indicates addition of H₂O₂. Representative traces from 5 separate experiments are shown. Control – vehicle treatment; H₂O₂ (1 mM); PQQ (10 μM); MnTBAP (10 μM); CsA (200 nM). PQQ, MnTBAP, and CsA were administered for at least 30 minutes prior to H₂O₂. Cells were treated with the mitochondrial uncoupler FCCP (1 μM) at the end of each experiment.
(B) Bar graph of average TMRM fluorescence (F) normalized to baseline (F_o) at indicated timepoints after H₂O₂ exposure and treatment with PQQ (gray bars) or MnTBAP (black bars). ** p<0.01 compared to time=0, n=3-5.