AJP - GI Fuel your research with LabChart
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Gastrointest Liver Physiol 270: G701-G707, 1996;
0193-1857/96 $5.00
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Guzman, M.
Right arrow Articles by Castro, J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Guzman, M.
Right arrow Articles by Castro, J.

AJP - Gastrointestinal and Liver Physiology, Vol 270, Issue 4 701-G707, Copyright © 1996 by American Physiological Society

ARTICLES

Effects of extracellular ATP on hepatic fatty acid metabolism

M. Guzman, G. Velasco and J. Castro
Department of Biochemistry and Molecular Biology I, Faculty of Biology, Complutense University, Madrid, Spain. mgp@solea.quim.ucm.es

Incubation of rat hepatocytes with extracellular ATP inhibited acetyl-CoA carboxylase (ACC) activity and fatty acid synthesis de novo, with a concomitant decrease of intracellular malonyl-CoA concentration. However, both carnitine O-palmitoyltransferase I (CPT-I) activity and ketogenesis from palmitate were inhibited in parallel by extracellular ATP. The inhibitory effect of extracellular ATP on ACC and CPT-I activities was not evident in Ca2+ -depleted hepatocytes. Incubation of hepatocytes with thapsigargin, 2,5-di-(t-butyl)-1,4-benzohydroquinone (BHQ), or A-23187, compounds that increase cytosolic free Ca2+ concentration ([Ca2+]i), depressed ACC activity, whereas CPT-I activity was unaffected. The phorbol ester 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA) increased ACC activity, whereas it decreased CPT-I activity in a nonaddictive manner with respect to extracellular ATP. The inhibitory effect of extracellular ATP on ACC activity was also evident in the presence of bisindolyl-maleimide, a specific inhibitor of protein kinase C (PKC), whereas this compound abolished the extracellular ATP-mediated inhibition of CPT-I. In addition, the PMA-induced inhibition of CPT-I was not potentiated by thapsigargin, BHQ, or A-23187. Results thus show 1) that the intracellular concentration of malonyl-CoA is not the factor responsible for the inhibition of hepatic long-chain fatty acid oxidation by extracellular ATP, and 2) that the inhibition of ACC by extracellular ATP may be mediated by an elevation of [Ca2+]i, whereas CPT-I may be inhibited by extracellular ATP through a PKC-dependent mechanism.


This article has been cited by other articles:


Home page
 Am. J. Physiol. Gastrointest. Liver Physiol.Home page
R. M. Roman, A. P. Feranchak, K. D. Salter, Y. Wang, and J. G. Fitz
Endogenous ATP release regulates Cl- secretion in cultured human and rat biliary epithelial cells
Am J Physiol Gastrointest Liver Physiol, June 1, 1999; 276(6): G1391 - G1400.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online