Enhanced Na+-Ca2+ exchange activity in cardiomyopathic Syrian hamster

Stephane N. Hatem, James S.K. Sham, Martin Morad

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


The signaling of contraction by Ca2+ in the Syrian hamster (BIO 14.6) heart in the late stage of the cardiomyopathy (220 to 300 days old) was compared with that in age-matched healthy hamster hearts. Membrane current and cell shortening or intracellular Ca2+ transients were measured simultaneously in isolated whole-cell-clamped myocytes. The density of the L-type Ca2+ current was smaller in myopathic than in normal myocytes (2.13±0.3 versus 3.21±0.4 pA/pF at 0 mV, P<.05). In both control and myopathic myocytes, the L-type Ca2+ current gated the release of Ca2+ and activation of contraction. In myopathic myocytes, activation of contraction also activated a slowly inactivating inward current of 1.73±0.2 pA/pF. The Na+-Ca2+ exchanger generated this current (INa-Ca), because it was suppressed by rapid replacement of Na+ with Li+ and depletion of the intracellular Ca2+ pool by caffeine. INa-Ca, activated by rapid application of caffeine, was not significantly different in both groups (3.7±0.5 pA/pF in control hearts versus 3.9±0.5 pA/pF in cardiomyopathic hearts). The activation of the inward exchanger current in myopathic myocytes coincided with a significant prolongation of contraction and the intracellular Ca2+ transient and a delay in the onset of relaxation. These results suggest that the enhanced activity of the Na+-Ca2+ exchanger may be related to compromised sequestration of Ca2+ in these animals.

Original languageEnglish (US)
Pages (from-to)253-261
Number of pages9
JournalCirculation research
Issue number2
StatePublished - Feb 1994
Externally publishedYes


  • Ca transients
  • Cardiomyopathy
  • Na-Ca exchange

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology


Dive into the research topics of 'Enhanced Na+-Ca2+ exchange activity in cardiomyopathic Syrian hamster'. Together they form a unique fingerprint.

Cite this