Key result
Adult human atrial myocytes exhibited transient outward current (Ito) in 100% of cells compared to 67% in young myocytes, with an almost twofold increase in current density.
Observational (n=28)
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In an effort to understand the ionic basis for the developmental changes that have been reported to occur in the configuration of the human atrial action potential, we characterized the transient outward current (Ito) and the inward rectifier current in atrial myocytes isolated from 20 young (ages 1 day-2.5 yr) and 8 adult (11-68 yr) human hearts using the whole cell patch-clamp technique. We found evidence for statistically significant (P < 0.05) age-related changes in the Ito, including 1) the presence of an Ito in only 67% of the cells isolated from young hearts vs. 100% of the cells isolated from adult hearts, 2) an almost twofold increase in the current density of Ito in adult cells vs. young cells, and 3) recovery kinetics that are approximately twofold slower in young myocytes relative to adult myocytes. In contrast, there were no age-related changes found in the current density of the inward rectifier current or the sustained current measured after the decay of Ito. These results suggest important current-dependent changes that occur with age in human atria.
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Crumb et al. (1995) conducted an observational in Healthy/Normal (Human atrial myocytes) (n=28). Adult age vs. Young age (1 day-2.5 yr) was evaluated on Presence of transient outward current (Ito) (p=< 0.05). Adult human atrial myocytes exhibited transient outward current (Ito) in 100% of cells compared to 67% in young myocytes, with an almost twofold increase in current density.
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