Na+/Ca2+ exchange and cell contraction in isolated neonatal and adult rabbit cardiac myocytes

An investigation conducted on neonatal cardiac myocyte contraction in rabbits finds that the cardiac myocyte contraction is non dependent on Ca2+ entry via voltage-gated Ca2+ currents, but that Ca2+ influx via reverse Na+/Ca2+ exchanger plays an important role in supporting systolic function in the developing heart. A major portion of the Ca2+, regulating the cell contraction during depolarization to positive membrane potentials, is provided by the Ca2+ entry via reverse Na+/Ca2+ exchanger.