Title: Gluconeogenesis is not acutely regulated by either plasma glucose or plasma insulin concentration in parenterally fed ELBW infants Authors
|Ordonez, Jorge - BAYLOR COLLEGE OF MEDICIN|
|Hays, Stephane - BAYLOR COLLEGE OF MEDICIN|
Submitted to: Pediatric Academic Society
Publication Type: Abstract Only
Publication Acceptance Date: December 16, 2006
Publication Date: May 6, 2007
Citation: Sunehag, A.L., Ordonez, J.M., Hays, S.P. 2007. Gluconeogenesis is not acutely regulated by either plasma glucose or plasma insulin concentration in parenterally fed ELBW infants [abstract]. Pediatric Academic Societies Annual Meeting, May 5-8, 2007, Toronto, Canada. Abstract No. 6430.6. Technical Abstract: Parenterally fed ELBW infants often exhibit erratic regulation of plasma glucose levels in response to changes in glucose infusion rate. This apparent dysregulation could be the result of an inappropriate insulin secretory response, incomplete suppression of glucose production, or an inadequate change in peripheral glucose uptake. The objective is to determine in ELBW infants whether rates of glucose production and gluconeogenesis are acutely regulated by glucose infusion rates or plasma concentrations of insulin and/or glucose. Six infants (BW 851 +/- 74 g, GA 26 +/- 1 wks) were studied on day 3 +/- 1 of life. All infants received total parenteral nutrition providing glucose at 8.2 +/- 0.5 mg/kg min (12 g/kg d); lipids (Intralipid) at 1.2 +/- 0.2 mg/kg min (1.8 g/kg d) and amino acids (TrophAmine) at 2.1 +/- 0.1 mg/kg min (3 g/kg d). Intralipid and TrophAmine were continued at the pre-study rates throughout the 11 h study period. Glucose was given at the pre-study rate for the first 5 h, was then reduced first to 6 mg/kg min (normal infant glucose turnover rate) for 1 h and subsequently to 3 mg/kg min (1/2 normal infant glucose turnover rate) for the remaining 5 h of the study. [U-13C]glucose constituted 2.6 mg/kg min of the total glucose infusion rate in order to measure glucose production (by isotope dilution) and gluconegenesis (by mass isotopomer distribution analysis). At the end of the first 5 h period (representing pre-study TPN), blood glucose was 6.8 +/- 0.7 mM and plasma insulin 26 +/- 5 U/mL. These concentrations had decreased to 4.6 +/- 0.6 mM (p=0.03) and 7 +/- 1 uU/mL (p=0.008), respectively, at the end of the 5 h period of glucose infusion at 3 mg/kg min. At the end of the first and second 5 h period, respectively, glucose production rates were 2.5 +/- 0.3 and 2.6 +/- 0.3 mg/kg min, and rates of gluconeogenesis 2.1 +/- 0.3 and 1.9 +/- 0.3 mg/kg min, i.e. unchanged by either the lower glucose concentration or reduction in circulating insulin level. In parenterally fed ELBW infants, decreasing the glucose infusion rate by 60%, resulted in a reduction of blood glucose by 30% and plasma insulin by 70%, but had no impact on rates of glucose production and gluconeogenesis. These data indicate that none of these processes respond to decrements in circulating concentrations of insulin and glucose within the normal range.