Studies on the effects of low-molecular uraemic toxins on the activity of 3-phospho-D-glycerol aldehyde dehydrogenase (E.C.1.2.1.12) in human erythrocytes.

The effects of known low-molecular uraemic toxins, such as guanidine, guanidinoacetic acid, creatinine, ornithine, or urea, on the activity of 3-phosphoglycerol aldehyde dehydrogenase (GDH) were studied in normal human erythrocytes. The study was carried out in vitro. Cyclic adenosine monophosphate in doses exceeding its physiological concentration was found also to exert an effect on GDH activity. The study demonstrated that various toxins affected the activity of the enzyme in various degrees depending on the type of the toxin and its concentration. Cyclic AMP in a concentration approximating that in the plasma of uraemic patients (10(-6) mol/l) inhibited 32.8% of GDH in the erythrocytes. A similar phenomenon was demonstrated also when the studied substances were given jointly.