Key result
Sarcoplasmic reticulum calcium content and release, as assessed by postrest contraction and rapid-cooling contracture, are not impaired in dogs during E. coli sepsis.
Depressed left ventricular contractility during E. coli sepsis in dogs is not due to impaired sarcoplasmic reticulum calcium content or release.
Rules out SR calcium impairment as cause of septic myocardial depression in dogs; hypothesis-generating for mechanisms in clinical sepsis.
We examined whether depressed left ventricular (LV) contractility during Escherichia coli sepsis in dogs was due to a decrease in the fractional release of calcium from the sarcoplasmic reticulum (SR) or a reduction in calcium content in this organelle. To indirectly assess SR calcium availability in a right ventricular (RV) trabecular muscle preparation, we utilized functional indexes of cellular myocardial calcium metabolism, which included rapid-cooling contracture (RCC), an indicator of SR calcium content, and postrest contraction (PRC), an index of calcium availability from the release compartment of the SR. Measurements were made during steady-state stimulation at 0.5 and 1.5 Hz, during which time rest intervals of 30-240 s were periodically imposed. SR calcium availability was measured in RV trabeculae of dogs subjected to 4 h of E. coli sepsis and was compared with calcium availability measured in nonseptic dogs. We further characterized a filterable cardiodepressant substance (FCS), which has been previously shown to be associated with LV depression in this model, to determine whether it produced changes in calcium metabolism similar to those found in sepsis. The results showed that calcium availability from the SR of septic dogs was not impaired. Furthermore, FCS was found in the 10,000- to 30,000-mol wt fraction of plasma and produced changes in PRC in canine trabeculae that were similar to those produced during sepsis. We conclude that, as assessed by PRC and RCC, SR calcium content and release are not impaired in sepsis.
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Jha et al. (1993) studied E. coli sepsis. E. coli sepsis and filterable cardiodepressant substance (FCS) vs. Nonseptic dogs was evaluated on Sarcoplasmic reticulum (SR) calcium availability (assessed by rapid-cooling contracture and postrest contraction). Sarcoplasmic reticulum calcium content and release, as assessed by postrest contraction and rapid-cooling contracture, are not impaired in dogs during E. coli sepsis.
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