Mouse mammary epithelium produces a soluble heat-sensitive macromolecule that inhibits differentiation of 3T3-L1 preadipocytes.

Coculture of normal mouse mammary gland (NMMG) epithelial cells with 3T3-L1 preadipocytes resulted in inhibition of triglyceride accumulation. This inhibition was also observed when the NMMG cells were grown in inserts and placed within a 100-mm dish containing confluent 3T3-L1 cells. As the number of NMMG-containing inserts was increased, there was a progressive decline in triglyceride content of the 3T3-L1 cells.

Differentiation of 3T3-L1 preadipocytes with 3-isobutyl-1-methylxanthine and dexamethasone stimulates cell-associated and soluble chondroitin 4-sulfate proteoglycans.

The proteoglycans (cell-associated and culture media) in 3T3-L1 preadipocytes in culture were analyzed before and during differentiation into adipocytes. Cells were metabolically labeled with [35S]sulfate and [3H] glucosamine for 24 h and then extracted and analyzed. There was a 1.

Synthesis of inactive nonsecretable high mannose-type lipoprotein lipase by cultured brown adipocytes of combined lipase-deficient cld/cld mice.

Combined lipase deficiency (cld) is a recessive mutation which causes a severe deficiency of lipoprotein lipase and hepatic lipase activities and lethal hypertriacylglycerolemia within 3 days in newborn mice. The effect of this genetic defect on lipoprotein lipase was studied in primary cultures of brown adipocytes derived from tissue of newborn mice. Cells cultured from cld/cld mice replicated, accumulated triacylglycerol, and differentiated into adipocytes at normal rates.

Multiple interactions of unsaturated fatty acids with opiate and ouabain binding sites and beta-adrenergic sensitive adenylate cyclase system.

The unsaturated fatty acids oleic, linoleic and arachidonic inhibited binding of ligands to the ouabain, opiate, and beta-adrenergic plasma membrane receptors. Low concentrations of fatty acids slightly increased the binding of ouabain to its binding sites. The effect of these fatty acids on beta-adrenergic sensitive adenylate cyclase was more complex.

Restricted passage of insulin across capillary endothelium in perfused rat adipose tissue.

Passage of insulin across capillary endothelium was monitored in perfused rat parametrial adipose tissue by the effect of intra-arterially infused insulin on oxidation of [U-14C]glucose to CO2. Glucose oxidation was constant at 34 nmol C.g-1.

Effect of heparin on membrane associated clathrin basketwork of cultured cells derived from the stromal-vascular fraction of mouse brown adipose tissue.

The effect of heparin treatment on clathrin basketwork of cell membranes was examined in cultured cells derived from the stromal-vascular fraction of neonatal mouse brown adipose tissue. The cytoplasmic surface of the plasma membrane of ruptured cells was examined with surface replicas. Heparin treatment significantly decreased the extent of clathrin basketwork associated with the membrane from 3.

Synthesis and secretion of lipoprotein lipase in 3T3-L1 adipocytes. Demonstration of inactive forms of lipase in cells.

3T3-L1 adipocytes in culture incorporated [35S]methionine into a protein which could be immunoprecipitated with chicken antiserum to bovine lipoprotein lipase. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed this protein had an Mr of 55,000, similar to that of bovine lipoprotein lipase, and accounted for 0.1-0.

The ouabain receptor in animal tissues and its endogenous ligand.

Cardiac glycosides bind to the Na+,K+-ATPase and inhibit its activity. Low concentrations (less than 10(-7) M) of ouabain stimulate the activity of Na+,K+-ATPase in whole homogenates of rat brain. The magnitude of this stimulation varies from 5 to 70%.

Effect of the combined lipase deficiency mutation (cld/cld) on ultrastructure of tissues in mice. Diaphragm, heart, brown adipose tissue, lung, and liver.

Lipoprotein lipase and hepatic lipase activities are very low in tissues of mice born with genetic combined lipase deficiency (cld/cld). Consequently, if allowed to suckle, the mice develop severe hyperlipemia and die within 3 days. The ultrastructure of capillaries and parenchymal cells in tissues that normally contain lipoprotein lipase and hepatic lipase was studied in tissues from cld/cld and unaffected mice 6 to 24 hours of age.

Effect of combined lipase deficiency (cld/cld) on hepatic and lipoprotein lipase activities in liver and plasma of newborn mice.

Combined lipase deficiency (cld/cld) is a recessive mutation in mice which results in massive hyperlipemia and death within 3 days after birth. We studied the effect of this deficiency on lipolytic activities in liver and in pre- and postheparin plasma of mice less than 2 days old. Anti-hepatic lipase serum inhibited more than 85% of the lipolytic activity in liver and plasma of normal newborn mice when assayed in high-salt medium, validating the use of this medium for measuring hepatic lipase activity in mice.

Effect of epinephrine and other lipolytic agents on intracellular lipolysis and lipoprotein lipase activity in 3T3-L1 adipocytes.

3T3-L1 adipocytes were used to test the hypothesis that hormone-sensitive lipolysis and lipoprotein lipase activity might be regulated in a reciprocal manner. Intracellular lipolysis was stimulated by catecholamine, dibutyryl cAMP, and ACTH, but not by glucagon. The effects of epinephrine on lipolysis were blocked by the beta-antagonist propanolol but not by the alpha-antagonist phentolamine.

Lipolysis of serum-activated triacylglycerol at the surface of J774.1 macrophages. A biochemical--electron-microscopic study.

Cultured mouse (J774.1) macrophages accumulated triacylglycerol, but no cholesteryl ester or cholesterol, when incubated in albumin-poor medium with serum-activated lipid particles containing 84 mol% trioleoylglycerol and 9 mol% cholesteryl oleate. Accumulation of triacylglycerol by cells was associated with hydrolysis of particulate triacylglycerol to fatty acid and glycerol.

Effect of pH on visualization of fatty acids as myelin figures in mouse adipose tissue by freeze-fracture electron microscopy.

We studied the effect of pH on visualization of fatty acids as myelin figures in young mouse epididymal adipose tissue. Fatty acid content of the tissue was increased to 12.4 nmol/mg wet weight by treating the tissue with 380 microM isoproterenol at pH 7.

Combined lipase deficiency (cld/cld) in mice. Demonstration that an inactive form of lipoprotein lipase is synthesized.

Combined lipase deficiency, cld, is a recessive mutation within the T/t complex of mouse chromosome 17. Mice homozygous for this defect display severe functional deficiencies of lipoprotein lipase and the related hepatic lipase. They develop massive hyperchylomicronemia and die within 3 days when allowed to suckle.

Clinical disorders associated with autoantibodies to the insulin receptor. Simulation by passive transfer of immunoglobulins to rats.

Patients with autoantibodies to the insulin receptor (Anti-R) may exhibit either fasting hypoglycemia or hyperglycemia and extreme insulin resistance. Occasionally, both these phenomena are observed in the same patient at different times in the clinical course. In an effort to understand what determines the patient's response to Anti-R, we developed an animal model of these clinical disorders by passive transfer of Anti-R IgG to rats.

Influence of glycogen on liver density: computed tomography from a metabolic perspective.

The liver is a metabolically active organ with a radiographic density that can be modified by its glycogen and fat content. In rhesus monkeys an increase in liver glycogen induced by glucose loading was accompanied by an increase in attenuation values on computed tomography and a decrease in total liver fat. Conversely, fasting depleted glycogen, increased fat, and decreased liver attenuation.

Lipoprotein lipase and uptake of triacylglycerol, cholesterol and phosphatidylcholine from chylomicrons by mammary and adipose tissue of lactating rats in vivo.

The relationship between lipoprotein lipase activity and uptake of triacylglycerol, cholesterol and phosphatidylcholine from chylomicrons was studied in mammary gland and adipose tissue of rats lactating 6--7 days. 60% of triacylglycerol [14C]oleic acid, 13% of [3H]cholesterol and 8% of [32P]phosphatidylcholine in chylomicrons injected intravenously were taken up within 11 min by mammary gland whereas negligible amounts were taken up by adipose tissue. Non-suckling for 44 h decreased markedly uptake of all lipids by mammary gland and retarded clearance of chylomicrons from blood, while it increased significantly uptake of triacylglycerol fatty acids and cholesterol by adipose tissue.

Lipoprotein lipase and uptake of chylomicron triglyceride by skeletal muscle of rats.

Uptake of chylomicron triglyceride and lipoprotein lipase was studied in red and white skeletal muscles, heart, and adipose tissue of rats. Retention of triglyceride fatty acids 10 min after injection was 1.6%/g in heart and adipose tissue, 0.

Effect of ACTH on lipolysis in adipose tissue of normal and adrenalectomized rats in vivo.

Parametrial fat-pads of fed rats were perfused in vivo. Rates of release of glycerol and free fatty acids (FFA) were determined from venous-arterial difference and plasma flow. Adrenalectomy lowered basal release of FFA and glycerol, but not reesterification of FFA within the fat-pad.