mortality/aging
• some mice die suddenly, predominantly between 4 - 8 weeks of age
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cardiovascular system
• at 6 - 8 weeks of age
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• at 6 - 8 weeks of age
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• bradyarrhythmia
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• bradyarrhythmia
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• significant prolongations of the atrial-His and His-ventricular intervals in perfused hearts
• slower conduction velocity and marked AP prolongation in the left ventricular epicardium of isolated hearts
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• most (82 of 105) mice display some degree of atrioventricular conduction block
• significant prolongations of the pacing cycle length at which Wenckebach-type AV block occurred and the effective refractory period of the AV node
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• prolonged PP and PQ intervals
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• prolonged duration
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• mean peak macroscopic voltage-gated Na+ current densities are dramatically reduced and recovery of currents from inactivation is delayed in ventricular cardiomyocytes
• slight increase in the sustained K+ current density
• decrease in peak L-type Ca2+ currents and a proportional reduction in the amplitude of the peak intracellular calcium transient
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