Journal: Pflugers Archiv

Article Title: The RyR2-P2328S mutation downregulates Na v 1.5 producing arrhythmic substrate in murine ventricles

doi: 10.1007/s00424-015-1750-0

Figure Lengend Snippet: MAP traces obtained from the epicardium of the left ventricle in WT and RyR2 S/S hearts during S1S2 pacing highlighting typical traces of either normal activity or arrhythmogenesis. All WT hearts entered the refractory period without displaying any episodes of arrhythmia, as defined by two or more non-stimulated APs ( a ); however, one heart displayed the occurrence of a singular ectopic (one non-stimulated AP) ( b ). Multiple arrhythmic events were observed in RyR2 S/S hearts including short non-sustained ventricular tachycardia (NSVT) ( c ), polymorphic tachycardia following a previously imposed S2 extrastimulus ( d ), monomorphic ventricular tachycardia (VT) ( e ) and episodes of VT which deteriorated into ventricular fibrillation (VF) (F). The small black circles indicate the timing of stimuli

Article Snippet: Hearts were paced at twice their excitation threshold voltage using a bipolar platinum-coated stimulating electrode placed on the ventricular septum connected to a DS2A-Mk.II stimulator (Digitimer).

Techniques: Activity Assay

Journal: Pflugers Archiv

Article Title: The RyR2-P2328S mutation downregulates Na v 1.5 producing arrhythmic substrate in murine ventricles

doi: 10.1007/s00424-015-1750-0

Figure Lengend Snippet: Typical MAP recordings obtained from the left ventricular epicardium of WT and RyR2 S/S during dynamic pacing. Traces from WT ( left ) and RyR2 S/S at progressively decreasing BCLs: 124 ( a ), 99 ( b ), 84 ( c ), 74 ( d ) and 54 ms ( e ). If a heart entered 2:1 block, the protocol was terminated (E). Traces are displayed along a common horizontal timescale. The vertical scale was normalized to a standard AP deflection at a BCL of 134 ms. Small black circles above each trace indicate the timing of stimuli

Article Snippet: Hearts were paced at twice their excitation threshold voltage using a bipolar platinum-coated stimulating electrode placed on the ventricular septum connected to a DS2A-Mk.II stimulator (Digitimer).

Techniques: Blocking Assay

Journal: Pflugers Archiv

Article Title: The RyR2-P2328S mutation downregulates Na v 1.5 producing arrhythmic substrate in murine ventricles

doi: 10.1007/s00424-015-1750-0

Figure Lengend Snippet: Total Cx43 expression in WT and RyR2 S/S ventricles. a Representative blots of Cx43 and GAPDH expression in WT and RyR2 S/S ventricular tissue and b the mean (± SEM) Cx43 expression normalized to GAPDH expression. Cx43 expression was similar between WT and RyR2 S/S (0.59 ± 0.07 and 0.79 ± 0.1, respectively; P = 0.167, n = 4) ventricles

Article Snippet: Hearts were paced at twice their excitation threshold voltage using a bipolar platinum-coated stimulating electrode placed on the ventricular septum connected to a DS2A-Mk.II stimulator (Digitimer).

Techniques: Expressing

Journal: Pflugers Archiv

Article Title: The RyR2-P2328S mutation downregulates Na v 1.5 producing arrhythmic substrate in murine ventricles

doi: 10.1007/s00424-015-1750-0

Figure Lengend Snippet: Western blots of Na v 1.5 expression in whole tissue and membrane fraction samples from WT and RyR2 S/S ventricles. Ventricular Na v 1.5 expression was decreased in RyR2 S/S compared to WT, both in the whole tissue (1.17 ± 0.20; n = 6, vs 1.69 ± 0.15 n = 7, respectively, P = 0.048) and in the membrane fraction (0.91 ± 0.13; n = 4, vs 2.06 ± 0.33; n = 4, respectively, P = 0.006). This suggested a greater proportional reduction in membrane relative to total Na v 1.5 expression in RyR2 S/S . Symbols denote significant differences between genotypes * P < 0.05, ** P < 0.01

Article Snippet: Hearts were paced at twice their excitation threshold voltage using a bipolar platinum-coated stimulating electrode placed on the ventricular septum connected to a DS2A-Mk.II stimulator (Digitimer).

Techniques: Western Blot, Expressing, Membrane

Journal: Pflugers Archiv

Article Title: The RyR2-P2328S mutation downregulates Na v 1.5 producing arrhythmic substrate in murine ventricles

doi: 10.1007/s00424-015-1750-0

Figure Lengend Snippet: Loose patch clamp recordings of I Na activation in WT and RyR2 S/S ventricles. a Representative currents in response to depolarizing steps increased from 20 to 120 mV in voltage-clamped WT and RyR2 S/S ventricular tissue. b Peak inward current (mean ± SEM) elicited at each voltage step for WT ( n = 6) and RyR2 S/S ( n = 12) ventricles. c The maximum current recorded during each complete voltage step protocol (mean ± SEM) was larger in the WT than the RyR2 S/S ventricles, P < 0.0047. The asterisks denote significant differences between genotypes of P < 0.01

Article Snippet: Hearts were paced at twice their excitation threshold voltage using a bipolar platinum-coated stimulating electrode placed on the ventricular septum connected to a DS2A-Mk.II stimulator (Digitimer).

Techniques: Patch Clamp, Activation Assay