Effects of Adenine Nucleotides and Microsomes on Glucose Utilization in Rat Heart Homogenates

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Abstract
The utilization of glucose by rat heart homogenate may proceed rapidly at low concentrations of ATP when conditions are such that this nucleotide is rapidly regenerated. When high concentrations of ATP are present, glucose utilization is depressed markedly. The inhibition of glucose metabolism is abolished completely by magnesium ions. Glucose is utilized at a rapid rate by a system consisting of heart mitochondria and the soluble components of a heart homogenate. The addition of microsomes to such a system produces a large increase in the rate of glucose disappearance and a decrease in the concentration of ATP. The stimulatory effect of microsomes appears to be mainly a result of an increase in ATPase activity. A possible role for ATP and magnesium in the regulation of glucose phosphorylation in the intact heart has been discussed.