Excitation-contraction uncoupling during ischemia in the blood perfused dog heart |
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Authors: | M J Levine K Harada A J Meuse J Watanabe J Breall J P Carrozza L Bentivegna A Franklin R G Johnson W Grossman |
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Affiliation: | Charles A. Dana Research Institute, Boston, MA. |
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Abstract: | The bioluminescent of Ca(2+)-indicator, aequorin, was loaded into the left ventricular apex of blood-perfused hearts from 13 dogs for simultaneous recording of left ventricular pressure and intracellular calcium levels. During a 2 minute period of ischemia, systolic and diastolic pressures significantly decreased. In contrast, these pressure changes were associated with an increase in both systolic and diastolic calcium reaching a maximum diastolic value of 0.59 microM and a systolic value of 1.11 microM. This apparent dissociation between pressure and [Ca2+]i supports the hypothesis that changes in myofilament Ca2+ responsiveness are of major importance in modulating contractility during ischemia in large mammalian hearts. |
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