A recently discovered hexosediphosphate, known as fructose 2,6 bisphosphate has been determined to be a potent regulator of gluconeogenesis and glycolysis in hepatic tissue. Increased levels are associated with increased glycolytic rate via a positive effect on 6 phosphofructol-kinase, while gluconeogenesis is reciprocally regulated by a negative effect on fructose 1,6 bisphosphatase. In the kidney, preliminary results demonstrate high levels of this effector in glycolytic renal medulla and low levels in gluconeogenic cortex.
The aims of this proposal are to determine the levels of F2, 6P2 in renal tissue isolated from rat renal cortex and medulla; to determine the kinetics and properties of the synthesizing enzyme, 6-phosphofructo-2 kinase (PFK-2) and to determine the activity of F 2,6 P2 and PFK-2 in tissue form diabetic animals. Rats with streptozotocin -diabetes or a BB/W autoimmune species will be studied. Diabetes is a state of increased renal gluconeogenesis. The independent effects of ketoacidosis and hyperglycemia will be determined. Another aim is to determine the hormonal regulation of F2,6 P2 levels in kidney tissue. Hormones, known to have renal effects on glucose metabolism (insulin, angiotensin II, parathyroid hormone and epinephrine) as well as glucagon, a potent regulator of F2, 6P2 in liver, will be tested for effects on activation of PFK-2. Finally, proximal tubule cells, grown in primary culture will be used to study the effects of ambient glucose concentrations and pH on F2,6P2 and to correlate glycolytic or gluconeogenic activity with activity of the pentose phosphate pathway.
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