Kinetic behavior and protein expression of hepatic NADPH-production systems during development of rainbow trout (Oncorhynchus mykiss)

We have studied the evolution of the kinetic behavior of main NADPH-generat ing systems, glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH), malic enzyme (ME) and isocitrate dehydogenase NADP-d ependent (NADP-IDH) in liver of rainbow trout at different developmental st ages. Our results show that during development, liver growth was due to an increase in the number of cells. Under these conditions, the main kinetic p arameters and pattern of protein expression of these enzyme systems did not change in any of the developmental stages studied. However, when the value s of these kinetic parameters were expressed in terms of cell units, we fou nd progressive and significant decreases in all enzymes assayed as fish siz e increased, indicating that during development, the liver makes less total NADPH available to the cell. (C) 1999 Elsevier Science B.V. All rights res erved.