Reduction in the Ca2(+)-induced Ca2+ release from canine cardiac sarcoplasmic reticulum following endotoxin administration.
Effects of endotoxin administration on the Ca2(+)-induced Ca2+ release from canine cardiac sarcoplasmic reticulum (SR) were studied. Results show that the Ca2(+)-induced Ca2+ release from either passively or actively loaded SR vesicles was decreased by 28 to 46% (p less than 0.05) 4 h after endotoxin administration. Kinetic analysis reveals that the Vmax for Ca2+ was decreased significantly without changing the S0.5 and the Hill coefficient values. The binding of [3H]ryanodine to cardiac SR was reduced by 25.3% (p less than 0.01) following endotoxin administration. These data demonstrate that the Ca2(+)-induced Ca2+ release via the ryanodine-sensitive Ca2+ channel in canine cardiac SR was reduced during endotoxin shock. A reduction in the SR Ca2(+)-induced Ca2+ release may have a pathophysiological significance in contributing to the development of myocardial depression during endotoxin shock.
Liu
M S
MS
Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, MO 63104.
Wu
L L
LL
D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D004285:Dogs; D004731:Endotoxins / Q000494:pharmacology; D004926:Escherichia coli; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D012016:Reference Values; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D012772:Shock, Septic / Q000378:metabolism*
D004731:Endotoxins; D008070:Lipopolysaccharides; D002118:Calcium