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Showing papers on "Fatty acid-binding protein published in 1980"


Journal ArticleDOI
TL;DR: Modulation of triglyceride-rich lipoprotein production by six steroids appears to be mediated to a significant extent by their effects on hepatic fatty acid utilization, and reflects in part the influence of sex steroids.
Abstract: The mechanism by which sex steroids influence very low density hepatic lipoprotein triglyceride production has not been fully elucidated In previous studies we showed that [(14)C]oleate utilization and incorporation into triglycerides were greater in hepatocyte suspensions from adult female rats than from males The sex differences were not related to activities of the enzymes of triglyceride biosynthesis, whereas fatty acid binding protein (FABP) concentration in liver cytosol was greater in females These findings suggested that sex differences in lipoprotein could reflect a sex steroid influence on the availability of fatty acids for hepatocellular triglyceride biosynthesis In the present studies, sex steroid effects on hepatocyte [(14)C]oleate utilization and FABP concentration were investigated directly Hepatocytes from immature (30-d-old) rats exhibited no sex differences in [(14)C]oleate utilization With maturation, total [(14)C]oleate utilization and triglyceride biosynthesis increased moderately in female cells and decreased markedly in male cells; the profound sex differences in adults were maximal by age 60 d Fatty acid oxidation was little affected Rats were castrated at age 30 d, and received estradiol, testosterone, or no hormone until age 60 d, when hepatocyte [(14)C]oleate utilization was studied Castration virtually eliminated maturational changes and blunted the sex differences in adults Estradiol or testosterone largely reproduced the appropriate adult pattern of [(14)C]oleate utilization regardless of the genotypic sex of the treated animal In immature females and males, total cytosolic FABP concentrations were similar In 60-d-old animals, there was a striking correlation among all groups (females, males, castrates, and hormone-treated) between mean cytosolic FABP concentration on the one hand, and mean total [(14)C]oleate utilization (r = 091) and incorporation into triglycerides (r = 094) on the other In 30-d-old animals rates of [(14)C]oleate utilization were greater, relative to FABP concentrations, than in 60-d-old animals The sex differences that characterize fatty acid utilization in adult rat hepatocytes are not present in cells from immature animals, and reflect in part the influence of sex steroids It remains to be determined whether the observed relationship of hepatic FABP concentration to [(14)C]oleate utilization in adult cells is causal or secondary to changes in cellular fatty acid uptake effected through another mechanism In either case, modulation of triglyceride-rich lipoprotein production by six steroids appears to be mediated to a significant extent by their effects on hepatic fatty acid utilization

119 citations


Journal ArticleDOI
TL;DR: Rat liver cytosol contains proteins and smaller molecules that affect activities of the microsomal enzymes of cholesterol biosynthesis, and one protein appears to be very similar to Z-protein that has been shown by others to be identical with hepatic fatty-acid binding protein.

84 citations


Journal ArticleDOI
TL;DR: Experiments involving proteolysis, inhibitors and competitive inhibition suggest that a fatty acid binding protein is responsible for the carrier process and this carrier protein seems to be present in increased amounts both in the supernatant and in the peroxisomes after clofibrate induction.

78 citations


Journal ArticleDOI
A. Gangl, W. Kornauth, J. Mlczoch, O. Sulm, B. Klose 
01 Feb 1980-Lipids
TL;DR: Data show that despite equal initial uptake by intestinal mucosa unsaturated long chain fatty acids taken up from plasma are esterified to a higher and oxidized to a lower extent than saturated plasma free fatty acids.
Abstract: During fat absorption, unsaturated long chain fatty acids are esterified at a higher rate than saturated fatty acids of similar chain length This phenomenon has been attributed to differences in the binding affinity of fatty acids to a cytosolic fatty acid-binding protein As intestinal mucosa utilizes plasma free fatty acids as well, we investigated whether long chainplasma free fatty acids of different degree of saturation are metabolized also at different rates3H-Palmitic and14C-linoleic acid complexed to rat serum were injected rapidly into a tail vein of fasting rats One, 2 and 4 min later there was no difference between3H and14C-radioactivity in intestinal mucosa, suggesting equal initial uptake of the two labeled fatty acids from plasma Despite their equal uptake, the incorporation of the isotopes into ester lipids was significantly different, however: at 2 min, 531±39% of3H and 738±46% of14C were recovered in ester lipids Phospholipids and triglycerides accounted for most of the mucosal3H and14C At 4 min, a similar distribution of isotopes in intestinal mucosal metabolites was found These data show that despite equal initial uptake by intestinal mucosa unsaturated long chain fatty acids taken up from plasma are esterified to a higher and oxidized to a lower extent than saturated plasma free fatty acids Unsaturated plasma free fatty acids, therefore, may provide a more important source of fatty acids for endogenous intestinal lipoprotein lipids than saturated plasma free fatty acids It is speculated that the fatty acid binding protein might be operative not only in the intracellular transport and metabolism of luminal fatty acids but of plasma free fatty acids as well

11 citations