Calcium Responsiveness in Regional Myocardial Short-term Hibernation and Stunning in the In Situ Porcine Heart

Abstract
Background We tested the hypothesis that decreased calcium responsiveness is responsible for the reduction in contractile function in regional hibernating and stunned myocardium in situ. Methods and Results In 19 anesthetized swine, the left anterior descending coronary artery flow was reduced to decrease anterior myocardial work index (sonomicrometry) by ≈60%. During 90 minutes of hypoperfusion, creatine phosphate recovered (as determined by biopsy specimens and bioluminescence) and no necrosis developed (as determined by staining with triphenyl tetrazolium chloride). In 10 swine, changes in the intracellular calcium concentration were induced by systematic variation of the postextrasystolic time interval at a constant prematurity. In 9 additional swine, a graded IC calcium infusion was performed. Under control conditions, anterior myocardial work increased with a fully compensated postextrasystolic time interval from 380±93 (mean±SD) to 523±98 mm Hg·mm. IC calcium infusion increased anterior myocardial ...

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