NADH is used in the determination of aldolase, glutamate dehydrogenase, transaminases, a-hydroxybutyrate dehydrogenase, lipase, malate dehydrogenase, sorbitol dehydrogenase, nucleoside monophosphate, nucleoside diphosphate, nucleoside triphosphate, ammonia, carbon dioxide, creatinine, free fatty acuds, uric acid urea nitrogen, pyruvate, triglycerides and other enzymes and metabolites.

1. 0.1M Triethanolamine buffer/substrate, pH 7.6: 1.86 g TEA&HCl, 210 mg glycerate-3-P, 125 mg MgSO4&7H2O and 50 mg EDTA with 80 ml distilled water. Adjust pH to 7.6 with 1M NaOH-Na2 and adjust volume to 100 ml with distilled water.
2. 18.2 mM Sodium Pyruvate: 0.20 mg pyruvate-Na in 10 ml distilled water.
3. LDH, from rabbit muscle (5 mg protein/ml): 500 U/mg.

1. Dissolve 25 mg NADH in 25 ml distilled water in a volumetric flask.
2. Set spectrophotometer (equipped with strip chart recorder and temperature control) at 340 nm and 25°C.
3. Into a cuvette, pipette the following:

   Buffer          (1)     3.50 ml
   Sodium pyruvate (2)     0.50 ml
   

   Mix and read the absorbance A1.
4. Add 0.10 ml of the sample. Mix and read absorbance A2.
5. Start the reaction by adding 0.01 ml LDH. Mix and read absorbance A3.
6. Add an additional 0.01 ml LDH. Mix and read absorbance A4.