Contribution of sodium-calcium exchange to contraction and relaxation in developing human cardiac myocytes

T. Chin, T. Morgan, T. Kasmarek, Q. Chen, K. Ward

Research output: Contribution to journalArticlepeer-review


We have shown that the sarcoplasmic reticulum develops during the 2nd trimester in human fetal cardiac myocytes. We measured the contribution of Na-Ca exchange to contractions and relaxation in myocyte clusters and ventricular myocytes from 1st and 2nd trimester human fetal hearts, respectively. Studies were performed under the guidelines of IRB protocol # 5754-96. Myocytes were bathed in normal solution at 30° and field-stimulated at 0.25 Hz. Contractions were measured with an edge detector. During the 1st trimester, rapid application of Na-free external solution increased peak contractions and prolonged relaxation compared to baseline. During the 2nd trimester, there was a larger increase in contractions, and smaller change in relaxation. Cardiac Na-Ca exchanger mRNA levels (RT-PCR), increased between 1st and 2nd trimesters: did not change between the 2nd trimester, 3rd trimester and newborn; and decreased post-natally. The Na-Ca exchanger contributes to contractions in human fetal hearts. Inhibition of Na-Ca exchange during the 2nd trimester may have less effect on relaxation because the sarcoplasmic reticulum is functional.

Original languageEnglish (US)
Pages (from-to)A710
JournalFASEB Journal
Issue number5
StatePublished - Mar 20 1998
Externally publishedYes

ASJC Scopus subject areas

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics


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