Key result
Increasing free [Mg2+] to 1.5 mM reduces SR Ca2+ transport ~48% in stunned rabbit myocardium.
Why the study?
Myocardial stunning is associated with increased intracellular free [Mg2+], but its effect on sarcoplasmic reticulum Ca2+ pump function is unclear.
Population
Sarcoplasmic reticulum from Langendorff perfused, isovolumic rabbit hearts after 15 minutes of global ischemia
Comparison
1.5 mM free [Mg2+] vs 0.6 mM free [Mg2+]
Design
Preclinical experimental study
Authors
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Increased Mg2+ may worsen SR Ca2+ defects post-stunning; hypothesis-generating for postischemic dysfunction mechanisms.
Absolute Event Rate: 138% vs 263%
An increase in intracellular free Mg2+ after myocardial stunning exacerbates the inherent defect in SR Ca2+ ATPase, further impairing Ca2+ regulation and potentially contributing to diastolic and systolic dysfunction.
Krause et al. (1991) studied Myocardial stunning. Increase in intracellular free [Mg2+] vs. 0.6 mM free [Mg2+] was evaluated on Sarcoplasmic reticulum Ca2+ transport rate at 0.56 microM free Ca2+. In stunned rabbit myocardium, increasing free [Mg2+] from 0.6 to 1.5 mM reduced SR Ca2+ transport at 0.56 microM free Ca2+ from 263 to 138 nmol Ca2+.min-1.mg-1.
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