Alterations in myocardial lipid metabolism during lactation in the rat

1998 ◽  
Vol 275 (2) ◽  
pp. E265-E271 ◽  
Author(s):  
Xin Wang ◽  
David G. Hole ◽  
Teresa H. M. Da Costa ◽  
Rhys D. Evans
Keyword(s):  
Fatty Acid ◽  
Mechanical Performance ◽  
Marked Decrease ◽  
Low Density Lipoproteins ◽  
Nonesterified Fatty Acid ◽  
Low Density ◽  
Mechanical Function ◽  
Lipoprotein Lipase Activity ◽  
Very Low Density Lipoproteins ◽  
Lactating Mammary Gland

Metabolism of nonesterified fatty acid (palmitate, 1.1 mM) and triacylglycerol (TAG; triolein, 0.4 mM in the form of both rat chylomicrons and very low density lipoproteins) was studied in isolated perfused working hearts from fed nulliparous, lactating, and weaned rats. Hearts from virgin rats oxidized palmitate readily, but optimal cardiac mechanical performance occurred during perfusion with chylomicrons. In hearts from lactating dams, there was a significant increase in palmitate oxidation and a marked decrease in TAG oxidation from both chylomicrons and very low density lipoproteins compared with hearts from nulliparous animals. There was a concomitant decrease in lipoprotein lipase activity in hearts from lactating animals, and TAG in the absence of palmitate could not support optimal cardiac mechanical function. After litter removal, the changes in fatty acid and TAG metabolism observed in lactation returned to nulliparous values within 96 h. These results suggest that, during lactation, both exogenous and endogenous TAGs are directed away from heart and toward the lactating mammary gland; the heart, therefore, has to rely to a greater extent on nonesterified fatty acid for energy provision under these conditions.

scholarly journals Fatty acid specificity for the synthesis of triacylglycerol and phosphatidylcholine and for the secretion of very-low-density lipoproteins and lysophosphatidylcholine by cultures of rat hepatocytes

1988 ◽  
Vol 249 (3) ◽  
pp. 727-733 ◽  
Author(s):  
A Graham ◽  
V A Zammit ◽  
D N Brindley
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Transport System ◽  
Unsaturated Fatty Acids ◽  
Rat Hepatocytes ◽  
Low Density Lipoproteins ◽  
Low Density ◽  
Very Low Density Lipoproteins ◽  
Fatty Acid Specificity ◽  
Monolayer Cultures

1. The synthesis and secretion of glycerolipids by monolayer cultures of rat hepatocytes was measured by using radioactive choline, glycerol and fatty acids and by measuring the concentration of triacylglycerols in the cells. 2. The incorporation of glycerol into triacylglycerol and the accumulation of this lipid in hepatocytes showed little specificity for fatty acids, except for eicosapentaenoate, which stimulated least. Oleate was more effective at stimulating triacylglycerol secretion than were palmitate, stearate, arachidonate and eicosapentaenoate. 3. Linoleate, linolenate, arachidonate and eicosapentaenoate stimulated the incorporation of glycerol and choline into phosphatidylcholine that was secreted into the medium. By contrast, palmitate and stearate produced relatively high incorporations into the phosphatidylcholine that remained in the cells. 4. The incorporation of glycerol and choline into lysophosphatidylcholine in the medium was stimulated 2-3-fold by all of the unsaturated fatty acids tested, whereas palmitate and stearate failed to stimulate if the acids were added separately. When 1 mM-stearate was added with 1 mM-linoleate, the incorporation of linoleate into lysophosphatidylcholine was about 4 times higher than that of stearate. 5. It is proposed that the secretion of lysophosphatidylcholine by the liver could provide a transport system for choline and essential unsaturated fatty acids to other organs.

Ribonucleic acid synthesis in rat liver during fatty acid stimulated secretion of very low density lipoproteins

Biochimie ◽  
1978 ◽  
Vol 60 (8) ◽  
pp. 743-753 ◽  
Author(s):  
Alain Raisonnier ◽  
Marie-Elisabeth Bouma ◽  
Colette Salvat ◽  
Recaredo Infante
Keyword(s):  
Fatty Acid ◽  
Rat Liver ◽  
Ribonucleic Acid ◽  
Acid Synthesis ◽  
Low Density Lipoproteins ◽  
Low Density ◽  
Very Low Density Lipoproteins

scholarly journals Differences in the metabolism of very-low-density lipoproteins by isolated beating-heart cells and the isolated perfused rat heart. Evidence for collagenase-released extracellular lipoprotein lipase

1980 ◽  
Vol 186 (2) ◽  
pp. 431-438 ◽  
Author(s):  
O V Rajaram ◽  
M G Clark ◽  
P J Barter
Keyword(s):  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Rat Heart ◽  
Beating Heart ◽  
Low Density Lipoproteins ◽  
Heart Cells ◽  
Low Density ◽  
Lipoprotein Lipase Activity ◽  
Very Low Density Lipoproteins ◽  
Perfused Rat Heart

1. The metabolism of VLD lipoproteins (very-low-density lipoproteins) was studied in intact isolated beating-heart cells and isolated perfused rat heart from starved animals by using [14C]triacylglycerol fatty acid-labelled VLD lipoprotein prepared from rats previously injected with [1-14C]palmitate. 2. 14C-labelled VLD lipoprotein was metabolized by the isolated perfused heart, but was only minimally metabolized by the heart cells unless an exogenous source of lipoprotein lipase was added. 3. Measurements of lipoprotein lipase at pH 7.4 with the natural substrate 14C-labelled VLD lipoprotein indicated that during collagenase perfusion of the heart the enzyme was released into the perfusate, the activity released being proportional to the concentration of collagenase used. Lipoprotein lipase activity in homogenates of hearts that had been perfused with collagenase showed a corresponding loss of activity. 4. At high perfusate concentrations of collagenase, inactivation of the released lipoprotein lipase occurred. 5. Lipoprotein lipase activity was largely undetectable in the homogenate of the isolated heart cells. 6. It is concluded that the lipoprotein lipase responsible for the hydrolysis of VLD lipoprotein triacylglycerol is predominantly located externally to the heart muscle cells and that its release can be facilitated by perfusion of the heart with bacterial collagenase.

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