AJP - Gastrointestinal and Liver Physiology, Vol 273, Issue 1 158-G163, Copyright © 1997 by American Physiological Society
Exposure to cigarette smoke delays the plasma clearance of chylomicrons and chylomicron remnants in rats
X. M. Pan, I. Staprans, D. A. Hardman and J. H. Rapp
Department of Veterans Affairs Medical Center, San Francisco, California, USA.
We investigated the effects of cigarette smoke exposure on the clearance of
chylomicrons (CM) and CM remnants in rats after administration of a
fat-containing meal. There was a decrease in clearance of both postprandial
CM and exogenous radiolabeled CM in smoke-exposed animals. For exogenous
CM, clearance (t1/2) increased significantly for both triglyceride and
cholesterol labels and correlated with the delay in liver uptake. This
decrease in lipid clearance could not be explained by decreased lipoprotein
lipase (LPL) activity because smoke exposure resulted in a significant
increase in LPL activity. When the hydrolysis of CM by endothelial LPL was
tested in a heart perfusion system, there was no difference in CM
hydrolysis between the two groups. Hepatic lipase activity was also
unchanged in smoke-exposed animals. However, there was a significant delay
in the CM remnant uptake into livers isolated from smoke-exposed rats. Thus
the delay in CM clearance in smoke-exposed animals cannot be attributed to
reduced lipase activities but results from impaired hepatic uptake of CM
remnants.
