Characterization of antilipolytic action of polyamines in isolated rat adipocytes.

The interactions of polyamines with the lipolytic system were studied in isolated rat adipocytes. Spermine, spermidine and putrescine significantly inhibited adenosine deaminase-stimulated lipolysis. An antilipolytic effect of spermine was detectable at a concentration of 0.

Polyamines in rat adipocytes: their localization and their effects on the insulin receptor binding.

Effects of polyamines on the insulin binding in isolated rat adipocytes were studied. In addition, the concentration of polyamines in adipose tissue was determined, and their localization revealed by fluorescence cytochemistry and immunocytochemistry. Spermine (0.

The effects of metformin on adipocyte insulin action and metabolic control in obese subjects with type 2 diabetes.

To investigate the mechanisms of action of metformin, insulin receptor binding and the activity of several insulin-controlled metabolic pathways were measured in adipocytes taken from 10 obese Type 2 diabetic patients treated for 4 weeks with either metformin (0.5 g x 3 daily) or matching placebo using a double-blind crossover design. Metformin therapy was associated with a significant fall in serum fructosamine levels (3.

A mixed meal potentiates the insulin sensitivity of glucose transport and metabolism in adipocytes from patients with type 2 diabetes mellitus.

Post-glucose enhancement of insulin action may represent a physiological mechanism for the acute regulation of insulin sensitivity of target tissues. To clarify whether a similar mechanism is operative in the insulin-resistant diabetic state we have investigated the effects of a mixed meal on adipocyte insulin action in eight patients with Type 2 diabetes mellitus. Ninety minutes after ingestion of breakfast insulin binding to fat cells increased by 21% (p less than 0.

Characterization of the insulin resistance of glucose utilization in adipocytes from patients with hyper- and hypothyroidism.

Unlabelled: Insulin action on glucose utilization was characterized in adipocytes from 10 thyrotoxic patients, 6 hypothyroid patients and 10 age- and sex-matched control subjects. In thyrotoxic patients insulin binding at low insulin concentrations was reduced (P less than 0.05) and accompanied by impaired insulin sensitivity of glucose transport (P less than 0.

Evidence that phorbol ester-activated pathways are not directly involved in the action of insulin in rat adipocytes.

The effects of 12-phorbol 13-myristate acetate (PMA) on glucose transport, glucose metabolism and lipolysis in rat adipocytes were examined. Alone, PMA (100 ng/ml) stimulated 2-deoxyglucose transport, glucose oxidation and lipogenesis by an amount corresponding to about 30-50% of the maximal insulin effect. The effect of PMA on the insulin-stimulated processes was additive at all insulin concentrations.

Interaction of indomethacin with the antilipolytic effect of prostaglandin E2 in rat adipocytes.

The interaction of indomethacin with the antilipolytic effect of prostaglandin E2 (PGE2) was investigated in rat adipocytes in order to reveal a possible role of endogenous PGs in adipose tissue. Adipocytes isolated from rats treated in vivo for 5 days with indomethacin were compared with non-treated control rats. The sensitivity of the antilipolytic effect of exogenous PGE2 was significantly enhanced in adipocytes from indomethacin-treated rats (IC50 of PGE2: 0.

Comparative studies of insulin binding to receptor from adipocytes, hepatocytes, monocytes and erythrocytes from the pig. Similarities with insulin receptor binding in man.

We have described the receptor binding of A14-labelled [125I]insulin to viable adipocytes, hepatocytes, monocytes and erythrocytes from the pig. For all cell types the binding was of high affinity, specific for insulin, the non-specific binding low and degradation of insulin in the medium was minimal. At 24 degrees C, steady state insulin binding was achieved in all four cell types.

Prostaglandin E2 action and binding in human adipocytes: effects of sex, age, and obesity.

The antilipolytic effect of prostaglandin E2 (PGE2) was studied in subcutaneous human adipocytes. The influence of sex, age, and obesity on the PGE2 effect was investigated. The antilipolytic effects of PGE2 were related to the PGE2 binding data obtained in the same adipocytes.

Alpha 2- and beta-adrenergic receptor binding and action in gluteal adipocytes from patients with hypothyroidism and hyperthyroidism.

The alpha 2- and beta-adrenergic receptor activities have been investigated in human adipocytes in relation to thyroid status. Adipocytes from 11 hypothyroid and 18 hyperthyroid were compared with 19 euthyroid (normal) subjects. The lipolytic and cAMP responses to isoproterenol and epinephrine were greatly enhanced in adipocytes from hyperthyroid subjects (P less than .

Factors regulating the production of prostaglandin E2 and prostacyclin (prostaglandin I2) in rat and human adipocytes.

The regulation of PGE2 (prostaglandin E2) and PGI2 (prostaglandin I2; prostacyclin) formation was investigated in isolated adipocytes. The formation of both PGs was stimulated by various lipolytic agents such as isoproterenol, adrenaline and dibutyryl cyclic AMP. During maximal stimulation the production of PGE2 and PGI2 (measured as 6-oxo-PGF1 alpha) was 0.

Antilipolytic effect of prostaglandin E2 in perifused rat adipocytes.

Previously, the antilipolytic effect of prostaglandin E2 (PGE2) has been investigated in conventional adipocyte incubations. To define the effect of PGE2 on lipolysis more clearly, isolated epididymal adipocytes were studied with the perifusion system. PGE2 inhibited isoproterenol (100 nM)- and theophylline (1 mM)-stimulated lipolysis in a concentration-dependent manner in both the perifusion system and conventional incubations.

Prostaglandin-E2 receptors in the rat kidney: biochemical characterization and localization.

A radiohistochemical technique yielding data on the distribution and characteristics of PGE2-receptor binding in tissue sections is described. The binding of tritiated PGE2 (3H-PGE2) to slide-mounted tissue sections had all the characteristics associated with ligand-receptor interactions: it was saturable, of high affinity and displayed high specificity for PGE2 binding. From the binding curves a Hill coefficient of 1.

Diabetic retinopathy after 3 years' treatment with continuous subcutaneous insulin infusion (CSII).

Twenty-four insulin-dependent juvenile diabetics with no or minimal background retinopathy were randomly allocated to conventional insulin therapy (CIT) or continuous sc insulin infusion (CSII) administrated by a portable pump. At the present 3 year follow-up, there was one drop-out in the CSII group. Although the metabolic control was significantly better in the CSII patients, both groups improved significantly in metabolic control during the observation period.

Increased alpha 2- but similar beta-adrenergic receptor activities in subcutaneous gluteal adipocytes from females compared with males.

alpha 2 and beta-adrenergic binding and action were studied in subcutaneous adipocytes from the gluteal region in females and males. The beta-selective antagonist [3H]dihydroalprenolol and the alpha 2-selective antagonist [3H]yohimbine were used to identify the beta- and the alpha 2-receptor, respectively. The biological effects mediated by these receptors were determined by measuring the glycerol release induced by isoproterenol (beta-receptor agonist) and by clonidine (alpha 2-receptor agonist).

Reduced binding and antilipolytic effect of prostaglandin E2 in adipocytes from patients with hyperthyroidism.

The present study was undertaken to evaluate the effect of thyroid hormones on prostaglandin E2 (PGE2) binding and action in human adipocytes. The study consisted of 12 patients with hyperthyroidism and 20 normal subjects. In adipocytes from hyperthyroid patients, there was a 32% decrease in [3H]PGE2-binding sites (P less than 0.

Continuous subcutaneous insulin infusion fails to correct impaired basal glucose metabolism and impaired insulin sensitivity of adipocytes from patients with type 1 (insulin-dependent) diabetes.

Studies of the in vivo insulin action in conventionally treated Type 1 diabetic patients have shown insulin resistance, especially in poorly controlled patients. We reported previously on impaired basal and insulin-stimulated glucose utilization in adipocytes from Type 1 diabetic subjects. In this study we have examined whether a near-normalization of glycaemia and plasma levels of metabolites in Type 1 diabetic patients induced by continuous subcutaneous insulin infusion might reverse abnormalities of adipose tissue metabolism.

Alpha 2-adrenergic binding and action in human adipocytes. Comparison between binding to plasma membrane preparations and to intact adipocytes.

Binding of the alpha 2-adrenoceptor antagonist [3H]yohimbine was demonstrated on intact human adipocytes and on human adipocyte membranes. Specific binding was rapid, reversible, saturable and of high affinity in both preparations. [3H]Yohimbine binding was inhibited by various adrenergic agents in a manner which suggests that the labeled sites probably represent the alpha 2-receptor both in intact adipocytes and in the membrane fraction.

Glucose transport and metabolism in adipocytes from newly diagnosed untreated insulin-dependent diabetics. Severely impaired basal and postinsulin binding activities.

Previous studies have shown cellular insulin resistance in conventionally treated insulin-dependent diabetics. To determine whether insulin resistance is also present in insulin-dependent diabetics before the commencement of insulin therapy, we studied nine newly diagnosed untreated insulin-dependent diabetics and nine control subjects. Insulin binding to adipocytes, monocytes, and erythrocytes was normal in the diabetic individuals.

Effect of insulin pump treatment for one year on renal function and retinal morphology in patients with IDDM.

The effect of strict metabolic control for 1 yr on renal function and retinal morphology was estimated in 24 insulin-dependent diabetic individuals (age 29 +/- 8 yr, diabetes duration 10 +/- 6 yr) with Albustix negative urine and minimal or no background retinopathy before the study. They were randomized to conventional insulin treatment (CIT) or continuous subcutaneous insulin infusion (CSII) with a portable pump. During CSII treatment the metabolic status was significantly improved and glomerular filtration rates (GFR) were found to decline (from 130 +/- 18 to 116 +/- 15 ml/min/1.

Defective non-insulin-mediated and insulin-mediated glucose transport and metabolism in adipocytes from obese and lean patients with untreated type 2 diabetes mellitus.

Insulin binding, glucose transport, and glucose metabolism were investigated in isolated adipocytes from 11 lean and 13 obese patients with non-insulin-dependent diabetes mellitus. Insulin binding at 15 degrees C was reduced by 35% (p less than 0.01) in both lean and obese diabetic patients, whereas insulin binding (or uptake) at 37 degrees C was similar in diabetic patients and healthy controls.

Postbinding defects of insulin action in human adipocytes from uremic patients.

It is now well established that longstanding human uremia is associated with impaired in vivo insulin action on glucose utilization of peripheral target tissues. In an attempt to define the cellular basis of the uremic insulin resistance we studied insulin action in adipocytes from eight patients with undialyzed chronic uremia and from eight matched healthy controls. (125I)-Insulin binding to fat cells from uremic patients was normal.

Effects of prostaglandin E2, indomethacin and adenosine deaminase on basal and insulin-stimulated glucose metabolism in human adipocytes.

The effects of prostaglandin E2 were studied on glucose metabolism (3-O-methylglucose transport, CO2 production and lipogenesis) in human adipocytes. Initially, the effects of endogenously produced adenosine and prostaglandins were indirectly demonstrated by using adenosine deaminase and indomethacin in the incubations. From these studies it was found that adenosine deaminase (5 micrograms/ml) had a pronounced effect on adipocyte glucose metabolism in vitro.

Increased insulin binding is not involved in the improved insulin effectiveness of gestational diabetics after hypoenergetic dieting.

125I-Insulin binding to monocytes from 14 gestational diabetics was measured before and after 6 weeks of treatment with a 5500 kJ, low-fat, low-sucrose diet. After the hypoenergetic feeding of gestational diabetics, fasting plasma concentrations of glucose (P less than 0.01) and insulin (P less than 0.