{"title":"The effect of fasting on the secretion of lipoproteins and two forms of apo B by perfused rat liver.","authors":"J B Marsh, C E Sparks","doi":"10.3181/00379727-170-41415","DOIUrl":null,"url":null,"abstract":"Abstract Rat livers from animals fed ad lib or fasted 24 hr were perfused by the single pass technique with 3H-amino acids and label incorporation into lipoprotein apoproteins was measured. The lipoproteins were separated into very low density lipoproteins (d < 1.006), low-density lipoproteins (1.006 < d < 1.06), and high-density lipoproteins (1.06 < d < 1.21) by ultracentrifugation and the apoproteins of each density fraction were analyzed by gel filtration column chromatography in the presence of sodium dodecyl sulfate. The apoprotein fractions included apo Bh (higher-molecular-weight apo B), apo B1 (lower-molecular-weight apo B), apo E, and apo C. Fasting decreased total hepatic apoprotein secretion from 75 to 53 μg·g−1·hr−1 and label incorporation into the apoproteins of very low density lipoproteins was reduced by 48% with the greatest reduction in both apo B fractions. There was a redistribution of apo Bh label into the low-density lipoproteins with fasting resulting in secretion of lipoproteins enriched in apo Bh. The high-density lipoprotein fraction contained 27 and 41% of the apo B1 label isolated from liver perfusates of fasted and fed animals, respectively. The nascent high-density lipoprotein was enriched in labeled apo B1 compared to low-density lipoproteins indicating that apo B in this density range represents a distinct metabolic fraction. With fasting the apo Bh and apo B1 apoproteins behave independently in terms of the distribution of label incorporation into nascent hepatic lipoproteins.","PeriodicalId":20675,"journal":{"name":"Proceedings of the Society for Experimental Biology and Medicine","volume":" ","pages":"178-81"},"PeriodicalIF":0.0000,"publicationDate":"1982-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3181/00379727-170-41415","citationCount":"26","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Proceedings of the Society for Experimental Biology and Medicine","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.3181/00379727-170-41415","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 26
Abstract
Abstract Rat livers from animals fed ad lib or fasted 24 hr were perfused by the single pass technique with 3H-amino acids and label incorporation into lipoprotein apoproteins was measured. The lipoproteins were separated into very low density lipoproteins (d < 1.006), low-density lipoproteins (1.006 < d < 1.06), and high-density lipoproteins (1.06 < d < 1.21) by ultracentrifugation and the apoproteins of each density fraction were analyzed by gel filtration column chromatography in the presence of sodium dodecyl sulfate. The apoprotein fractions included apo Bh (higher-molecular-weight apo B), apo B1 (lower-molecular-weight apo B), apo E, and apo C. Fasting decreased total hepatic apoprotein secretion from 75 to 53 μg·g−1·hr−1 and label incorporation into the apoproteins of very low density lipoproteins was reduced by 48% with the greatest reduction in both apo B fractions. There was a redistribution of apo Bh label into the low-density lipoproteins with fasting resulting in secretion of lipoproteins enriched in apo Bh. The high-density lipoprotein fraction contained 27 and 41% of the apo B1 label isolated from liver perfusates of fasted and fed animals, respectively. The nascent high-density lipoprotein was enriched in labeled apo B1 compared to low-density lipoproteins indicating that apo B in this density range represents a distinct metabolic fraction. With fasting the apo Bh and apo B1 apoproteins behave independently in terms of the distribution of label incorporation into nascent hepatic lipoproteins.