Hypoxia delays the intracellular Ca2+ clearance by Na+-Ca2+ exchanger in human adult cardiac myocytes.
Transient myocardial ischemia during cardiac surgery causes a loss of energy sources, contractile depression, and accumulation of metabolites and H+ ion resulting in intracellular acidosis. The reperfusion following ischemic cardioplegia recovers intracellular pH, activates Na+-H+ exchange and Na+-Ca2+ exchange transports and consequently produces Ca2+ overload, which yields cell death. Among the various Ca2+ entry pathways, the Na+-Ca2+ exchanger is known to play one of the major roles during the ischemia/reperfusion of cardioplegia. Consequently, information on the changes in intracellular Ca2+ activities of human cardiac myocytes via the Na+-Ca2+ exchanger is imperative despite previous measurements of Ca2+ current of human single myocytes. In this study, human single myocytes were isolated from the cardiac tissues obtained during open-heart surgery and intracellular Ca2+ activity was measured with cellular imaging techniques employing fluorescent dyes. We report that the Na+-Ca2+ exchanger of adult cardiac myocytes is more susceptible to hypoxic insult than that of young patients.
Park
S I
SI
Department of Physiology and Biophysics, Inha University College of Medicine, Inchon, Korea.
Park
E J
EJ
Kim
N H
NH
Baek
W K
WK
Lee
Y T
YT
Lee
C J
CJ
Suh
C K
CK
D000328:Adult; D002118:Calcium / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D000860:Hypoxia / Q000378:metabolism*; D007223:Infant; D008297:Male; D008875:Middle Aged; D019831:Sodium-Calcium Exchanger / Q000502:physiology*
D019831:Sodium-Calcium Exchanger; D002118:Calcium