The effect of insulin on the metabolism of human adipose tissue in vitro

Fessler, Alfred; Beck, John C.

doi:10.1016/0005-2760(65)90108-6

Cited by 27 publications

(11 citation statements)

References 14 publications

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“…The virtually identical patterns of basal and insulinstimulated lipogenesis from glucose in omental and subcutaneous fat cells provide further evidence which indicates that the metabolism of omental adipose tissue is basically similar to that of subcutaneous fat. The discrepancy between the present observations and those of earlier comparisons which showed higher rates of glucose oxidation, esterification, and neutral lipid synthesis in omental fat cells and pieces of omental adipose tissue (12,(26)(27)(28) may well be more apparent than real. Here, we have corrected the results for differences in the numbers of subcutaneous and omental fat cells, whereas this was not the case with earlier studies.…”

Section: Resultscontrasting

confidence: 99%

Lipolysis and lipogenesis from glucose in human fat cells of different sizes

Goldrick¹,

Mcloughlin²

1970

J. Clin. Invest.

151

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A B S T R A C T Lipogenesis from glucose and lipolysisin human omental and subcutaneous fat cells were studied as functions of adipose cell size and number in adult females. Since subcutaneous fat cells were larger than those prepared from the greater omentum, a comparison could be made of the metabolism of different sizes of cells within individual subjects. Rates per cell of glyceride-glycerol and glyceride-fatty acid synthesis from glucose were similar in omental and subcutaneous fat cells incubated in the presence or absence of insulin. However, subcutaneous fat cells exhibited higher rates of basal lipolysis than omental fat cells and these differences were maintained when lipolysis was stimulated with theophylline. Different rates of lipolysis were not demonstrable after incubations with epinephrine, indicating that subcutaneous fat cells were less responsive to this hormone than smaller omental fat cells. Correlation and partial correlation analysis showed that differences in basal and theophylline-stimulated lipolysis between fat cells prepared from different subjects and between omental and subcutaneous fat cells could be accounted for A precise evaluation of the influence of adipose cell enlargement on its function requires that metabolic studies be performed on fat cells of different sizes prepared from the same fat depot. In the present investigation we have used an indirect approach to the problem, taking advantage of the fact that human subcutaneous fat cells are generally larger than those prepared from the greater omentum. It was thus possible to carry out paired comparisons in vitro of the metabolism of differently sized fat cells derived from a common in vivo internal environment. The data from different subjects were also examined to determine whether there was a correlation between the volume and metabolism of a fatThe Journal of Clinical Investigation Volume 49 1970 1213 cell independent of factors such as age and relative body weight. We reasoned that if both sets of analyses showed that adipose cell volume was the common factor in accounting for differences in cellular function within and between subjects, then this would be strong supportive evidence for an effect of cellular enlargement on metabolism. METHODSSource of adipose tissue. Samples of fat (8-12 g) were obtained from the subcutaneous tissues of the anterior abdominal wall and from the greater omentum of 31 subjects who were undergoing elective abdominal surgery. Operations were performed in the mornings after an overnight fast. Morphine and atropine or their derivatives were used for premedication. Anesthesia was induced with thiopentone sodium and maintained with nitrous oxide and halothane. Tissues were removed between 60 and 90 min after induction of anesthesia. On the basis of previous reports (9, 10) it has been assumed that variations in the duration and depth of anesthesia did not significantly affect the metabolism of subcutaneous and omental fat cells in vitro.Relevant clinical data as well and individual values for a...

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Section: Resultscontrasting

confidence: 99%

Lipolysis and lipogenesis from glucose in human fat cells of different sizes

Goldrick¹,

Mcloughlin²

1970

J. Clin. Invest.

151

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“…The presence of connective tissue in adipose tissue segments would increase the time required for equilibration between medium and fat cell, as glucose will have to traverse additional space. That this indeed requires time has been shown for sorbitol in rat and human adipose tissue (6,21 (Figs. 5 and 6).…”

Section: Discussionmentioning

confidence: 69%

“…In light of the variable metabolic behavior of adipose tissue obtained from the different species of laboratory animals (2, 3), one might question the rele-vance of studies performed in the rat to human adipose tissue metabolism. As a matter of fact, recent data obtained in man seem to indicate that, contrary to the rat, human adipose tissue in vitro is insensitive to physiological doses of insulin (4)(5)(6)(7). This hypothesis carries important implications, as it would shift the emphasis from adipose tissue to the liver as 'the major site of fat synthesis.…”

Section: Introductionmentioning

confidence: 99%

Comparative Effects of Insulin on Adipose Tissue Segments and Isolated Fat Cells of Rat and Man*

Gries¹,

Steinke²

1967

J. Clin. Invest.

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Summary. In vitro metabolism of glucose-1-'4C by adipose tissue into 14CO2 and total 14C lipids in rat and man was compared employing both adipose tissue segments and isolated fat cells prepared from the same donor. In the rat, the basal glucose metabolism and response to insulin decreased with increasing body weight for both adipose tissue segments and isolated cells. Regardless of age, the isolated cells exhibited a persistently higher metabolic activity. Of the parameters selected, conversion to CO2 was more pronounced than that to lipid.In contrast to the rat, in man adipose tissue segments were more active than isolated cells. In four subjects, the effect of 6, 50, and 400 uU/ml of insulin was analyzed on conversion of glucose-i-carbon to CO2, long chain fatty acids, and glycerides by adipose tissue segments only. In 17 subjects, glucose oxidation and lipid synthesis by adipose tissue segments and isolated fat cells were measured and showed a definite response to physiological doses of crystalline pork insulin,. There was, however, an age dependency, and consistent effects were obtained with 6 FLU/ml in children and 50 puU/ml in adults. The responsiveness of human adipose tissue to exogenous insulin in concentrations comparable to those detected in blood reemphasizes the importance of adipose tissue as a major site for fatty acid synthesis.

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“…The P: 0 ratio for this oxidative pathway is less than 2 (15) compared to a P: 0 ratio of 3 for the oxidation of glucose to C02 through the Krebs cycle (o16)r.The glycerophosphate pathway, therefore, could serve as a regulator of the efficiency with which oxidation and phosphorylation are coupled. Increased activity of this pathway during high caloric intake would tend to decrease the caloric effi- (20,21) depends calories may occur in normal man and animals. With upon the preparation chosen for study (22)(23)(24), upon human subjects they showed that high caloric intake the previous caloric intake, as well as age (23) and the leads to enhanced thermogenesis (17,18).…”

Section: Discussionmentioning

confidence: 99%