Abstract
Summary
Rat cardiac tissue slices incubated in a 0.300 osmolar solution containing up to 0.100 osmol sodium or up to 0.025 osmol potassium and 1% glucose, synthesized acid-soluble glycogen. Greater synthesis of this glycogen fraction occurred in a glucose medium if the electrolytes were not present. A further increase of either ion induced glycogenolysis or depressed synthesis of this fraction. The acid-insoluble glycogen fraction was not especially sensitive to the electrolyte content of a solution but glycogenolysis was observed under all experimental conditions and increased as the electrolyte was increased. Oxygen consumption was highest in a 0.300 osmolar solution that contained approximately 1% glucose and 0.010 osmol of sodium and no potassium. As concentration of the electrolytes was increased oxygen utilization decreased. To extract the most information from glycogen synthesis studies the acid-soluble and acid-insoluble glycogen fractions should be investigated.
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