Glycolytic System

Glycolytic System

1. Pyruvate to Lactate

   • Lactate dehydrogenase accepts H- ions from pyruvate

2. History behind lactate

   • 1920's
     • Myerhoff – glycogen precursor to lactic acid
   • 1930's-1970's
     • metabolic dead end waste product.
   • 1980's
     • Tracer studies of Brooks and colleagues Lactate shuttle hypothesis

3. Lactate Shuttle

   • Lactate is both produced & used by muscle
     • Actively oxidised in working muscle
       • Fuel -for heart (highly oxidative) and type I
         • Recirculation in blood – cell-to-cell
     • Produced by type II and transported and used in type I - within cells

4. Cori Cycle

   • Gluconeogenesis

5. Facts about lactate

   • Lactate is a by-product of glucose utilisation regardless of O2 or CO2 being present
   • Lactate is cleared within an hour of most exercise
   • Hydrogen ions and other by-products from intense exercise are probably responsible for muscle burn not the lactate
   • Lactate Threshold
     • Believed to be a better indicator of endurance performance than VO2max
       • Occurs at around 50-60% of VO2max in untrained, 65- 80% in trained subjects

6. Stages of Glycolysis

   • The conversion of Glucose into pyruvic acid which turns into lactate
     • 1. Glucose/Glycogen
       • 2. Glucose 6-phosphate
         • 3. Fructose 6-phosphate
           • 4. Fructose 1, 6-bisphosphate
             • 5. 2 molecules of Glyceraldehyde, 3-phosphate
               • 6. 2 molecules of Bisphosphoglycerate, 3-phosphate
                 • 7. 2 molecules of phosphoglycerate, 3-phosphate
                   • 8. 2 molecules of phosphoglycerate, 2-phosphate
                     • 9. 2 molecules of phosphoenolpyruvate
                       • 10. 2 molecules of pyruvate
     • Net gain of ATP = 2

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