Cardiomyocyte ionic currents in intact young and aged murine Pgc-1 β−/− atrial preparations

Publication date: January 2018 Source:Mechanisms of Ageing and Development, Volume 169 Author(s): Haseeb Valli, Shiraz Ahmad, Anita Y. Jiang, Robert Smyth, Kamalan Jeevaratnam, Hugh R. Matthews, Christopher L.-H. Huang Introduction Recent studies reported that energetically deficient murine Pgc-1β−/− hearts replicate age-dependent atrial arrhythmic phenotypes associated with their corresponding clinical conditions, implicating action potential (AP) conduction slowing consequent upon reduced AP upstroke rates. Materials and methods We tested a hypothesis implicating Na+ current alterations as a mechanism underlying these electrophysiological phenotypes. We applied loose patch-clamp techniques to intact young and aged, WT and Pgc-1β−/− , atrial cardiomyocyte preparations preserving their in vivo extracellular and intracellular conditions. Results and discussion Depolarising steps activated typical voltage-dependent activating and inactivating inward (Na+) currents whose amplitude increased or decreased with the amplitudes of the activating, or preceding inactivating, steps. Maximum values of peak Na+ current were independently influenced by genotype but not age or interacting effects of genotype and age on two-way ANOVA. Neither genotype, nor age, whether independently or interactively, influenced voltages at half-maximal current, or steepness factors, for current activation and inactivation, or time constants for recovery from inactivation following repola...

Source: Mechanisms of Ageing and Development - December 11, 2017 Category: Geriatrics Source Type: research