Reduction in the Ca2(+)-induced Ca2+ release from canine cardiac sarcoplasmic reticulum following endotoxin administration |
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Authors: | M S Liu L L Wu |
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Affiliation: | Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, MO 63104. |
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Abstract: | 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. |
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