The overall objective of the proposed research is to investigate the metabolic myopathy and erythroenzymopathy in the first and newly discovered animal model of the human glycogen storage disease type VII and to evaluate various therapeutic strategies. An inherited muscle-type phosphofructokinase deficiency that causes hemolysis and mild exertional myopathy has recently been identified by the principal investigator in English Springer Spaniel dogs. A colony of affected animals will be established and the natural history and pathologic manifestations will be further characterized. The glycolytic defect in the skeletal muscle will be investigated in vivo and in situ by using phosphorus nuclear magnetic resonance 31P-NMR methods. The 31P-NMR signals from the anesthetized animals' hindlimb muscle can give information about the glycolytic metabolism and intracellular pH during resting, muscle stimulation,-ischemia and recovery. The influence of chemically well-defined diets including acute and chronic administration of fatty acids, amino acids and carbohydrates on normal and PFK-deficient muscle metabolism will be evaluated. Canine PFK deficient erythrocytes are depleted of 2,3-diphosphoglycerate leading to decreased tissue oxygenation and increased erythrocyte alkaline fragility. Intracellular pH of erythrocytes will be directly measured by 31p-NMR. Three therapeutic modalities are investigated: (1) Enhancing tissue oxygenation through increasing the erythrocyte 2,3-diphosphoglycerate content by various compounds used in blood transfusion medicine (2) decreasing the intracellular pH by carbonic anhydrase inhibitors, and (3) cellular manipulation using allotransplantation of bone marrow.
