Table 6.

Developmental changes in excitation-contraction coupling

Age range	Cardiomyocyte type	Key points	Citation
<1–75 years	Right ventricular	Age-dependent increase in ICa density	Cohen and Lederer (1993)
<1–75 years 1–8 years	Right atrial and ventricular Right ventricular	Age-dependent decrease in calcium window current	Cohen and Lederer (1993); Pelzmann et al. (1998)
<1–79 years	Right atria	Age-dependent increase in ICa amplitude Lower basal L-type calcium current amplitude and increased expression of inhibitory G proteins is seen in infant atrial cells, compared with adults	Tipparaju et al. (2004)
<1–79 years	Right atria	No age-dependent difference in ICa No evidence for age-related changes in ICa density, steady-state inactivation or recovery from inactivation	Roca et al. (1996)
<2 years <0–40 years	Left and right ventricle Ventricular	Age-dependent increase in calcium-handling proteins Age-dependent increase in NCX, SERCA, phospholamban and L-type calcium channel; age-dependent decrease in T-type calcium channel expression	Wiegerinck et al. (2009); Qu et al. (2000)
<1–4 years	Right atria	Excitation-contraction coupling matures with postnatal age Slower Ca2+ upstroke velocity in infant cells is likely to be attributable to structural immaturity and inefficient coupling between calcium channels and ryanodine receptors	Hatem et al. (1995)
<1 year	Right atria	Paediatric action potential waveform modulates excitation-contraction coupling Prolonged early repolarization in paediatric cells is correlated with increased dependence on trans-sarcolemmal Ca2+ influx for contraction	Wagner et al. (2005)
<2 years	Left and right ventricle	Age-dependent increase in force-frequency relationship At faster frequencies, newborn ventricular muscle strips have less developed force compared with slightly older infant muscle strips; results are likely to be linked to developmental changes in protein expression	Wiegerinck et al. (2009)