Sarcolemmal phospholipid asymmetry and Ca fluxes on metabolic inhibition of neonatal rat heart cells.
The present study examines the hypothesis that during depletion of high-energy phosphates a change will occur in the phospholipid topology and in Ca fluxes in cultured neonatal cells and that these two events may be causally related. A combination of 2-deoxyglucose and iodoacetic acid was used to produce graded changes in the adenine nucleotides in the cells. An on-line technique for 45Ca measurement was used to follow Ca uptake and compartmentation by the cells, and chemical and enzymatic probes were used to study sarcolemmal phospholipid topology. After 15 min of metabolic inhibition (ATP = 10% of control) an increase in cellular Ca occurs, which progresses with time. Over 70% of this Ca accumulates in the mitochondria. After 30 min of metabolic inhibition (ATP < 10% of control) a change in the phospholipid topology is observed, and an increased amount (two times control) of sarcolemmal phosphatidylethanolamine is present in the outer monolayer of the sarcolemma. This change in phospholipid topology was independent of the extracellular Ca concentration. The sequence of altered Ca fluxes and distribution followed by the altered phospholipid topology is discussed in terms of its possible role in the pathogenesis of sarcolemmal disruption.
Post
J A
JA
Department of Physiology, University of California Los Angeles School of Medicine 90024-1760.
Clague
J R
JR
Langer
G A
GA
D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D004734:Energy Metabolism; D005110:Extracellular Space / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D009994:Osmolar Concentration; D010710:Phosphates / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism*; D051381:Rats; D012508:Sarcolemma / Q000378:metabolism*; D014018:Tissue Distribution
D010710:Phosphates; D010743:Phospholipids; D007770:L-Lactate Dehydrogenase; D002118:Calcium