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Physiological consequences of the P2328S mutation in the ryanodine receptor (RyR2) gene in genetically modified murine hearts.

Acta physiologica (Oxford, England) (2008-04-19)
C A Goddard, N S Ghais, Y Zhang, A J Williams, W H Colledge, A A Grace, C L-H Huang
ABSTRACT

To explore the physiological consequences of the ryanodine receptor (RyR2)-P2328S mutation associated with catecholaminergic polymorphic ventricular tachycardia (CPVT). We generated heterozygotic (RyR2 p/s) and homozygotic (RyR2 s/s) transgenic mice and studied Ca2+ signals from regularly stimulated, Fluo-3-loaded, cardiac myocytes. Results were compared with monophasic action potentials (MAPs) in Langendorff-perfused hearts under both regular and programmed electrical stimulation (PES). Evoked Ca2+ transients from wild-type (WT), heterozygote (RyR2 p/s) and homozygote (RyR2 s/s) myocytes had indistinguishable peak amplitudes with RyR2 s/s showing subsidiary events. Adding 100 nm isoproterenol produced both ectopic peaks and subsidiary events in WT but not RyR2 p/s and ectopic peaks and reduced amplitudes of evoked peaks in RyR2 s/s. Regularly stimulated WT, RyR2 p/s and RyR2 s/s hearts showed indistinguishable MAP durations and refractory periods. RyR2 p/s hearts showed non-sustained ventricular tachycardias (nsVTs) only with PES. Both nsVTs and sustained VTs (sVTs) occurred with regular stimuli and PES with isoproterenol treatment. RyR2 s/s hearts showed higher incidences of nsVTs before but mainly sVTs after introduction of isoproterenol with both regular stimuli and PES, particularly at higher pacing frequencies. Additionally, intrinsically beating RyR2 s/s showed extrasystolic events often followed by spontaneous sVT. The RyR2-P2328S mutation results in marked alterations in cellular Ca2+ homeostasis and arrhythmogenic properties resembling CPVT with greater effects in the homozygote than the heterozygote demonstrating an important gene dosage effect.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
牛磺酸, ≥99%
Sigma-Aldrich
牛磺酸, suitable for cell culture, meets USP testing specifications
Supelco
牛磺酸, Pharmaceutical Secondary Standard; Certified Reference Material
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牛磺酸, BioUltra, ≥99.5% (T)
SAFC
牛磺酸
Sigma-Aldrich
牛磺酸, ≥98%, FG