Disappearance of two major phosphatidylcholines from plasma is
predominantly via lcat and hepatic lipase.
Shamburek, Robert D., Loren A. Zech, Patricia S. Cooper, Julie M.
Vandenbroek, and Charles C. Schwartz.
Department of Medicine, Division of Gastroenterology, Medical
College of Virginia, Virginia Commonwealth University, Richmond,
Virginia 23298; and National Institutes of Health/National Heart,
Lung, and Blood Institute, Bethesda, Maryland 20892
APStracts 3:0142E, 1996.
Metabolism of 1-stearoyl-2-arachidonyl-PC (SAPC), a major PC species
in rat plasma, was compared with 1-palmitoyl-2-linoleoyl-PC (PLPC).
HDL containing SAPC and PLPC tracers labeled in the sn-2 fatty acid
with 3H- and 14C-isotopes, respectively, was administered. The rats
were depleted of endogenous bile acids and infused via the ileum with
individual bile acids that ranged widely in hydrophobicity. The t 1/2
for SAPC and PLPC in plasma were 48 and 57 min, respectively. Most of
the 3H-activity that disappeared from plasma at 1h was found in the
liver in PAPC, SAPC and OAPC, indicating phospholipase A1 hydrolysis
of plasma SAPC forming 2-arachidonyl-lysoPC which was reacylated in
the liver. Plasma PLPC also underwent A1 hydrolysis as reported
previously. The fraction of 3H-dose that accumulated in plasma
cholesteryl arachidonate was 2-3-fold higher than 14C-dose in
cholesteryl linoleate. Multicompartmental models for SAPC and for
PLPC were developed that included lysoPCs and cholesteryl esters.
Bile acids did not influence plasma PC metabolism. LCAT and
phospholipase A1 (hepatic lipase) hydrolysis accounted for at least
90% of the SAPC and the PLPC that disappeared from plasma; SAPC and
PLPC are comparable as substrates for hepatic lipase, but SAPC is
preferred by LCAT.
Received 1 March 1996; accepted in final form 15 July 1996.
APS Manuscript Number E107-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 July 1996