The Role of Calcium and Phospholipase A2 in Glucagon-Induced Enhancement of Mitochondrial Calcium Retention
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Glucagon affects metabolic activities in different compartments of the liver cell, including the mitochondria. These effects of glucagon are often preserved during isolation of the mitochondria (see 1 for review). The mitochondrial actions of glucagon may not be directly mediated by a rise in the level of cAMP; instead, mitochondrial calcium uptake may be involved in transferring the hormonal signal to the mitochondrial matrix. Glucagon induces a mobilization of calcium from non-mitochondrial stores in hepatocytes, presumably by activation of the phosphoinositide-specific phospholipase C (2,3). This leads to a transient increase in cytosolic free calcium levels, disturbing the balance between matrix and cytosolic calcium concentrations maintained by the calcium transport systems present in the inner membrane. There is evidence that mitochondrial calcium content is increased after glucagon treatment (4).
KeywordsMitochondrial Calcium Intact Mitochondrion Cytosolic Calcium Concentration Calcium Retention Cytosolic Calcium Level
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