Key result
Increasing free Mg2+ to simulate reperfusion reduces SR Mg2+-ATPase Ca2+ sensitivity by ~50%.
Why the study?
The significance of the rise in intracellular free Mg2+ concentration after reperfusion on sarcoplasmic reticulum function in stunned myocardium is not well known.
Population
Sarcoplasmic reticulum isolated from Langendorff-perfused, isovolumic rabbit hearts after 15 min of reversible ischemia
Comparison
Increased free [Mg2+] (1.2 mM) simulating reperfusion vs control free [Mg2+] (0.6 mM)
Design
Preclinical experimental study
Authors
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May alter SR Ca2+ handling in reperfused myocardium; leaves open role in clinical stunning.
The sustained increase in intracellular free Mg2+ after myocardial stunning further impairs sarcoplasmic reticulum Ca2+ transport by decreasing the Ca2+ sensitivity of the SR Mg2+-ATPase.
Stephen M. Krause (1991) studied Myocardial stunning. Increased free [Mg2+]i vs. 0.6 mM free [Mg2+] was evaluated on Ca2+ sensitivity of the SR Mg(2+)-ATPase (50% activation). An increase in free [Mg2+] simulating reperfusion after stunning decreased the Ca2+ sensitivity of the SR Mg(2+)-ATPase, shifting 50% activation from 0.42 to 0.63 microM free [Ca2+].
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