Abstract. The levels of insulin-like growth factors (IGF), two somatomedin-like polypeptides of human serum and of their carrier protein were determined in sera of patients with various metabolic disorders. IGF was measured by 4 different methods (fat pad and fat cell assay and competitive protein binding assay measuring total IGF, and a radioimmunoassay for IGF I) after extraction by acidic gel filtration on Sephadex G-50. This procedure is necessary to separate IGF from the carrier protein, which interferes with all of these assays. 1) In normal serum, immunoreactive IGF I accounts for one third of total IGF determined by the fat pad assay, but only for one fifth to one sixth of immunoreactive IGF I + II. 2) In acromegalics total IGF was increased 1.5- (protein binding and fat cell assay) to 2-fold (fat pad assay), but the increase was solely due to immunoreactive IGF I, which was ∼ 5-times above normal. The IGF binding activity was not elevated. Total IGF and IGF binding were decreased in hypopituitarism, Laron-type dwarfism and in liver cirrhosis. Immunoreactive IGF I was more drastically reduced in these diseases than total IGF. Apparently, only IGF I is under growth hormone control. The liver seems to be involved in the production of IGF. 3) No elevation of total IGF was found in patients with extrapancreatic tumour hypoglycaemia, but IGF binding was reduced. Immunoreactive IGF I was decreased in 5 of 10 patients. These results suggest that tumour hypoglycaemia in our patients is unlikely to be caused by increased IGF levels. 4) In patients with hyperprolactinaemia neither total IGF nor immunoreactive IGF I were elevated, and IGF binding was unchanged. 5) In newly detected insulin-deficient juvenile diabetics total IGF and immunoreactive IGF I levels were within the normal range, although the variation was greater than in normal subjects. However, IGF binding was markedly decreased.

Summary.Insulin was absorbed faster from the abdomen than from the thigh under resting conditions and during exercise. Exercise enhanced the rate of insulin absorption marginally. The fall of blood glucose during rest and exercise was not significantly different after insulin injection into either site. The faster absorption of insulin from the abdomen during rest and exercise was reflected in a sharper rise of serum growth hormone levels and urinary adrenaline excretion. Therefore exercise should not be taken immediately after injection of a large dose of soluble insulin, particularly into the abdomen.Key words: Insulin, insulin absorption, plasma insulin, blood glucose, exercise, growth hormone, urinary catecholamines.Physical exercise is one of the three corner stones of the treatment of the insulin-dependent diabetic. However, the fluctuations of blood glucose during exercise often exceed the desirable range. Previous investigations have shown that the rate of absorption of subcutaneously injected insulin varies during physical exercise depending on the site of injection [1][2][3][4] in man and rat. These findings might explain the large variations of blood glucose during exercise, being mediated by faster absorption of insulin and/or an increased glucose uptake by the working muscle. A relatively good correlation has been established between the rate of insulin absorption and the decline of blood glucose in diabetic subjects [5][6][7][8][9], although it is weaker in normal subjects [91.The aims of this study were to determine in normal subjects 1) the effect on blood glucose after injecting insulin into the thigh compared with the abdomen, 2) the concentrations of insulin in plasma and of some counter-regulatory hormones under these conditions and 3) the influence of physical exercise on these metabolic indices. Subjects and MethodsFour young healthy subjects (mean age 24.5 years, range: 21-31 years; mean weight 66.7 + 7.1 kg and mean height 174.9 _+_ 7.7 cm) gave their informed consent to the following study. Each of the subjects was tested on six occasions: NaC1 was injected into the arm for basal values. Actrapid insulin (Novo) was injected (0.12 U/kg body weight) 20 cm above the upper edge of the patella in the median line or 4 cm to the side of the umbilicus. The skin was folded and the depth of injection was 0.5-0.7 cm. Each test was carried out twice; once under resting conditions and a second time during exercise, consisting of 50% of the working capacity calculated according to the Pulse-Watt-Capacity 170 in the upright position (87.5 _+ 6 W; ergometical working capacity at a pulse rate of 170/rain). The subjects worked three 15-min periods each separated by 5 min of rest. Venous blood samples were drawn through an indwelling catheter in the antecubital vein of the contralateral arm to the injection site at 0, 15, 45, 65, 85, 120 and 150 min. The following determinations were carried out: blood glucose (glucose oxidase, YSI-Glucose Analyser 23A), plasma insulin by radioimmunoassay (detection limit:...

Abstract. .Before cell cultures can be used as a tool for metabolic and endocrine research, standardized conditions for stationary and growing cells must be established. Our results with chicken embryo fibroblasts and with WI‐38 human fibroblasts demonstrate that the metabolic behaviour of these cells differs depending on whether they are in a stationary phase (without serum) or in a growing phase (with serum). Energy during growth is derived almost exclusively from glycolysis. Two additional factors determine the rate of glucose consumption and lactate production: The glucose concentration in the medium and the density of the cells, i.e. the number of cells per surface area. Using a pulse of labelled thymidine it can be shown that after a delay fibroblasts simultaneously go through the first S‐phase under the stimulatory influence of serum. Stationary cells behave metabolically as contact‐inhibited cells with regard to glucose consumption and lactate production. It appeals that serum triggers off a sequence of metabolic events including increased glycolysis, thymidine incorporation into DNA and growth.

Abstract. The effects of insulin and purified nonsuppressible insulin‐like activity from serum (NSILA‐S) on glucose, DNA‐metabolism and growth of chicken embryo fibroblasts are compared. Insulin stimulates growth, glucose consumption, lactate production and thymidine uptake only in very high concentrations (1–100 mU/ml), whereas NSILA‐S is effective at concentrations which may be present under physiological conditions. On a molar basis NSILA‐S is approximately 20 times as active as insulin. Although a potent stimulator of all these metabolic indices NSILA‐S can only partially replace serum. NSILA‐S may be one of the growth factors present in serum but it does not seem to be the only one.

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