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L-type calcium current in pediatric and adult human atrial myocytes: evidence for developmental changes in channel
T P Roca1, J D Pigott, C W Clarkson
1Department of Pediatrics, Tulane University School of Medicine, New Orleans, Louisiana 70112-2699, USA.
Insights
Human atrial myocytes show mature L-type calcium channels at birth. Pediatric cells exhibit faster calcium current inactivation, potentially explaining shorter action potentials in children compared to adults.
Area of Science:
- Cardiology
- Molecular Physiology
- Developmental Biology
Background:
- Animal studies show developmental changes in cardiac L-type calcium current.
- Understanding these changes in human hearts is crucial for pediatric cardiology.
Purpose of the Study:
- To characterize postnatal changes in human atrial L-type calcium current.
- To compare calcium current properties between pediatric and adult human atrial myocytes.
Main Methods:
- Whole-cell patch clamp technique was used.
- Atrial myocytes were isolated from pediatric (3 days to 14 years) and adult (43-79 years) human hearts.
Main Results:
- No age-related differences in calcium current density, inactivation, or recovery kinetics were observed.
- Pediatric atrial myocytes showed significantly faster calcium current inactivation (approx. 2-fold) compared to adult myocytes.
- Calcium channels appear functionally mature at birth in the human atrium.
Conclusions:
- Human atrial L-type calcium channels are largely mature at birth.
- Faster inactivation kinetics in pediatric atrial myocytes may contribute to shorter action potential duration.
- These findings offer insights into age-dependent electrophysiological differences in the human heart.
Abstract:
Animal studies have documented the presence of marked, species-dependent, developmental changes in the properties of the L-type calcium current in cardiac myocytes. In an effort to understand the postnatal changes which occur in the calcium current in human heart, we characterized the calcium current in atrial myocytes isolated from 17 pediatric and older children (ages 3 d to 14 y) and 12 adult (ages 43-79 y) human hearts using the whole-cell patch clamp technique. In contrast to animal models, we found no evidence for age-related changes in calcium current density, steady-state inactivation, or kinetics of recovery from inactivation, suggesting that, in human atrium, calcium channels are in many aspects functionally mature at the time of birth. However, statistically significant differences were found in the kinetics of calcium current inactivation, with calcium current measured in cells isolated from pediatric human atria inactivating approximately 2-fold faster than cells isolated from adult hearts. These results suggest a possible role for age-related changes in calcium current inactivation in the shortened action potential duration observed in pediatric compared with adult human atrium.