Faculty Collaboration Database

The role of glutamine and other alternate substrates as energy sources in the fetal rat lung type II cell. Pediatr Res 1996 Jul;40(1):135-41

Date

07/01/1996

Pubmed ID

8798259

DOI

10.1203/00006450-199607000-00023

Scopus ID

2-s2.0-0029977185 (requires institutional sign-in at Scopus site)   32 Citations

Abstract

Glucose has been thought to be the primary substrate for energy metabolism in the developing lung; however, alternate substrates are used for energy metabolism in other organs. To examine the role of alternate substrates in the lung, we measured rates of oxidation of glutamine, glucose, lactate, and 3-hydroxybutyrate in type II pneumocytes isolated from d 19 fetal rat lungs by measuring the production of 14CO2 from labeled substrates. Glutamine had a rate of 24.36 +/- 4.51 nmol 14CO2 produced/ h/mg of protein (mean +/- SEM), whereas lactate had a significantly higher rate, 40.29 +/- 4.42. 3-Hydroxybutyrate had a rate of 14.91 +/- 1.93. The rate of glucose oxidation was 2.13 +/- 0.36, significantly lower than that of glutamine. To examine the interactions of substrates normally found in the intracellular milieu, we measured the effect of unlabeled substrates as competitors on labeled substrate. This identifies multiple metabolic compartments of energy metabolism. Glucose, but not lactate, inhibited the oxidation of glutamine, suggesting a compartmentation of tricarboxylic acid cycle activity, rather than simple dilution by glucose. Glucose and lactate had reciprocal inhibition. Our data suggest at least two separate compartments in the type II cells for substrate oxidation, one for glutamine metabolism and a second for glucose metabolism. In summary, we have documented that glutamine and other alternate substrates are oxidized preferentially over glucose for energy metabolism in the d 19 fetal rat lung type II pneumocyte. In addition, we have delineated some of the compartmentation that occurs within the developing type II cell, which may determine how these substrates are used.

Author List

Fox RE, Hopkins IB, Cabacungan ET, Tildon JT

Author

Erwin Cabacungan MD Associate Professor in the Pediatrics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

3-Hydroxybutyric Acid
Animals
Carbon Radioisotopes
Embryonic and Fetal Development
Energy Metabolism
Gestational Age
Glucose
Glutamine
Hydroxybutyrates
Lactic Acid
Lung
Oxidation-Reduction
Pulmonary Surfactants
Rats
Rats, Sprague-Dawley