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Biomedical subjects

B Sonne

Publications and source records attributed to B Sonne.

At least 37 records · Page 2Linked to original sources
PubMed1985

Effect of physical training on glucose transporters in fat cell fractions.

Physical training increases maximally insulin-stimulated glucose assimilation and 3-O-methylglucose transport in epididymal fat cells. In the present report, glucose-inhibitable cytochalasin B binding in subcellular fractions of epididymal adipocytes was measured to assess changes in number of glucose transporters induced by training. Groups of rats trained by swimming were compared to control groups of the same age, matched with respect to body weight by restricted feeding. It was found that in trained rats the number of glucose transporters in the low density microsome fractions from non-insulin-stimulated fat cells was larger than in untrained rats. In both groups of rats, insulin stimulation of adipocytes decreased the number of glucose transporters in low-density microsomes by about 60% and increased the number of glucose transporters in the plasma membrane fractions. The number of glucose transporters in the plasma membrane fractions from maximally insulin-stimulated fat cells was larger in trained rats than in control rats. [U-14C]Glucose incorporation into lipids varied in proportion to plasma membrane cytochalasin B binding per cell under all conditions tested. The results explain the enhancing effect of training on insulin responsiveness transport of hexose in fat cells.

5'-Nucleotidase↗
PubMed1985

The effect of training on responses of beta-endorphin and other pituitary hormones to insulin-induced hypoglycemia.

We studied whether the previously reported intensified beta-endorphin response to exercise after training might result from a training-induced general increase in anterior pituitary secretory capacity. Identical hypoglycemia was induced by insulin infusion in 7 untrained (VO2max 49 +/- 4 ml X (kg X min)-1, mean and SE) and 8 physically trained (VO2max 65 +/- 4 ml X (kg X min)-1) subjects. In response to hypoglycemia, levels of beta-endorphin and prolactin immunoreactivity in serum increased similarly in trained (from 41 +/- 2 pg X ml-1 and 6 +/- 1 pg X ml-1 before hypoglycemia to 103 +/- 11 pg X ml-1 and 43 +/- 9 pg X ml-1 during recovery, P less than 0.05) and untrained (from 35 +/- 7 pg X ml-1 and 7 +/- 2 pg X ml-1 to 113 +/- 18 pg X ml-1 and 31 +/- 8 pg X ml-1, P less than 0.05) subjects. Growth hormone (GH) was higher 90 min after glucose nadir in trained (61 +/- 13 mU X l-1) than in untrained (25 +/- 6 mU X l-1) subjects (P less than 0.05). Levels of thyrotropin (TSH) changed in neither of the groups. It is concluded that, in contrast to what has been formerly proposed, training does not result in a general increase in secretory capacity of the anterior pituitary gland. TSH responds to hypoglycemia neither in trained nor in untrained subjects. Finally, differences in beta-endorphin responses to exercise between trained and untrained subjects cannot be ascribed to differences in responsiveness to hypoglycemia.

Adult↗
PubMed1985

Gastric acid secretory function in preterm infants.

To establish normal values for gastric secretory function in preterm infants, we studied 34 healthy preterm infants once a week during hospitalization. Basal acid output, pentagastrin-stimulated acid output, fasting serum gastrin, and fasting serum pancreatic polypeptide were measured during each study. Basal acid output at 1 week of age was 12 mumol/kg/hr, increasing over the first 4 weeks to 30 mumol/kg/hr. Administration of pentagastrin 6 micrograms/kg subcutaneously increased acid output in all age groups. Pentagastrin-stimulated acid output at 1 week was 21 mumol/kg/hr, increasing over the first 4 weeks to 44 mumol/kg/hr. Acid secretion did not change significantly over the next 4 to 6 weeks. Fasting serum gastrin concentration was stable over the first 6 weeks of life, but doubled during the end of the second month. Pancreatic polypeptide was found at low levels throughout the study. These studies confirm that the majority of healthy preterm infants secrete acid in quantity sufficient to maintain the gastric pH less than or equal to 4, providing a barrier to bacteria and protein antigens.

Achlorhydria↗
PubMed1985

Glucose turnover during insulin-induced hypoglycemia in liver-denervated rats.

The role of hepatic autonomic nerves in glucose production during hypoglycemia was studied. Selective, surgical denervation of the liver was performed in rats, which reduced hepatic norepinephrine concentrations by 96%. Hypoglycemia was induced by 250 mU of insulin intra-arterially in anesthetized as well as in chronically catheterized, awake rats. Half of the anesthetized denervated or sham-operated rats had previously been adrenodemedullated. Glucose turnover was measured by primed, constant intravenous infusion of [3-3H]glucose. Before as well as during hypoglycemia the arterial glucose concentration and rates of production and utilization of glucose were similar in denervated rats and control rats. Also hepatic glycogen depletion was similar in the groups. The lack of effect of denervation could not be ascribed to compensating changes in hormone or substrate levels. In adrenodemedullated rats lack of glucose recovery from hypoglycemia was accompanied by delayed normalization of glucose clearance. In fed rats, activity in hepatic autonomic nerves is not a primary mechanism increasing glucose production during acute hypoglycemia. Epinephrine enhances glucose recovery by decreasing glucose clearance rather than by increasing glucose production, at least when glucagon is present.

Adrenal Cortex Hormones↗
PubMed1985

Effect of exercise on epinephrine turnover in trained and untrained male subjects.

The kinetics underlying plasma epinephrine concentrations were studied. Six athletes (T) and six sedentary males (C) were given intravenous infusions of 3H-labeled epinephrine, after which arterial blood was drawn. They rested sitting and bicycled continuously to exhaustion (60 min at 125 W, 60 min at 160 W, 40 min at 200 W, and 240 W to the end). Work time was 154 +/- 13 (SE) (T) and 75 +/- 6 (C) min. At rest, epinephrine clearance was identical [28.4 +/- 1.3 (T) vs. 29.2 +/- 1.8 (C) ml . kg-1 . min-1], but plasma concentration [1.42 +/- 0.27 (T) vs. 0.71 +/- 0.16 (C) nmol . l-1] and, accordingly, secretion [2.9 +/- 0.7 vs. 1.5 +/- 0.4 nmol . min-1] were higher (P less than 0.05) in T than C subjects. Epinephrine clearance was closely related to relative work load, decreasing from 15% above the basal level at 30% of maximal O2 uptake (VO2 max) to 22% below at 76% of VO2 max. Epinephrine concentrations increased much more with work intensity than could be accounted for by changes in clearance and were, at exhaustion, higher (P less than 0.05) in T (7.2 +/- 1.6) than in C (2.5 +/- 0.7 nmol . l-1) subjects despite similar glucose, heart rate, and hematocrit values. At a given load, epinephrine clearance rapidly became constant, whereas concentration increased continuously. Forearm extraction of epinephrine invalidated use of blood from a cubital vein or a hand vein arterialized by hot water in turnover measurements. During exercise, changes in epinephrine concentrations reflect changes in secretion rather than in clearance. Training may increase adrenal medullary secretory capacity.

Adrenal Medulla↗
PubMed1985

Carbohydrate metabolism during and after exercise in rats: studies with radioglucose.

Carbohydrate metabolism in exercise, including regulation of glucose production, was studied by isotope-dilution methods, and these were evaluated. Chronically catheterized rats were examined before, during, and after 45 min of running at either low (LIE) or moderate (MIE) intensity. Glucose production (Ra) and disappearance (Rd), as well as muscular glycogen breakdown (Gly), were estimated by primed constant infusions of [3-3H]- and [U-14 C]glucose, and pyruvate oxidation was estimated by sampling of expired 14CO2. During exercise, Ra increased faster than Rd and was, as were steady-state glucose concentration (G) and Gly, directly related to exercise intensity. During recovery Ra and G decreased rapidly, but after MIE, G showed a rebound increase. 14C estimates and chemical measurements sometimes disagreed. Methodological evaluation showed marked incorporation of label in glycogen, lipid, and protein at rest and mobilization of label during exercise. 14CO2 recovery in expired air ranged from only 50% at rest to 77% during MIE. In conclusion, during exercise, mobilization of hepatic glycogen is a primary event and not secondary to increased muscular demand. During and after exercise, plasma glycogen is not precisely controlled at euglycemic levels. Isotope methods may be used to study carbohydrate metabolism in exercising rats, but the results (especially 14C data) should be interpreted with caution.

Animals↗
PubMed1985

Role of liver nerves and adrenal medulla in glucose turnover of running rats.

Sympathetic control of glucose turnover was studied in rats running 35 min at 21 m X min-1 on the level. The rats were surgically liver denervated, adrenodemedullated, or sham operated. Glucose turnover was measured by primed constant infusion of [3-3H]glucose. At rest, the three groups had identical turnover rates and concentrations of glucose in plasma. During running, glucose production always rose rapidly to steady levels. The increase was not influenced by liver denervation but was halved by adrenodemedullation. Similarly, hepatic glycogen depletion was identical in denervated and control rats but reduced after adrenodemedullation. Early in exercise, glucose uptake rose identically in all groups and, in adrenodemedullated rats, matched glucose production. Accordingly, plasma glucose concentration increased in liver-denervated and control rats but was constant in adrenodemedullated rats. Compensatory changes in hormone or substrate levels explaining the lack of effect of liver denervation were not found. In rats with intact adrenals, the plasma epinephrine concentration was increased after 2.5 min of running. It is concluded that, in rats carrying out exercise of moderate intensity and duration, hepatic glycogenolysis and glucose production are not influenced by the autonomic liver nerves but are enhanced by circulating epinephrine.

Adrenal Medulla↗
PubMed1984

Muscle and liver glycogen, protein, and triglyceride in the rat. Effect of exercise and of the sympatho-adrenal system.

We have previously found that during exercise net muscle glycogen breakdown is impaired in adrenodemedullated rats, as compared with controls. The present study was carried out to elucidate whether, in rats with deficiencies of the sympatho-adrenal system, diminished exercise-induced glycogenolysis in skeletal muscle was accompanied by increased breakdown of triglyceride and/or protein. Thus, the effect of exhausting swimming and of running on concentrations of glycogen, protein, and triglyceride in skeletal muscle and liver were studied in rats with and without deficiencies of the sympatho-adrenal system. In control rats, both swimming and running decreased the concentration of glycogen in fast-twitch red and slow-twitch red muscle whereas concentrations of protein and triglyceride did not decrease. In the liver, swimming depleted glycogen stores but protein and triglyceride concentrations did not decrease. In exercising rats, muscle glycogen breakdown was impaired by adrenodemedullation and restored by infusion of epinephrine. However, impaired glycogen breakdown during exercise was not accompanied by a significant net breakdown of protein or triglyceride. Surgical sympathectomy of the muscles did not influence muscle substrate concentrations. The results indicate that when glycogenolysis in exercising muscle is impeded by adrenodemedullation no compensatory increase in breakdown of triglyceride and protein in muscle or liver takes place. Thus, indirect evidence suggests that, in exercising adrenodemedullated rats, fatty acids from adipose tissue were burnt instead of muscle glycogen.

Adrenal Medulla↗
PubMed1984

Glucose turnover and hormonal changes during insulin-induced hypoglycemia in trained humans.

Eight athletes (T), studied the third morning after the last exercise session, and seven sedentary males (C) (maximal O2 consumption 65 +/- 4 vs. 49 +/- 4 (SE) ml X kg-1 X min-1, for T and C men, respectively) had insulin infused until plasma glucose, at an insulin level of 1,600 pmol X l-1, was 1.9 mmol X l-1. Glucose turnover was determined by primed constant rate infusion of 3-[3H]glucose. Basal C-peptide (0.46 +/- 0.04 vs. 0.73 +/- 0.06 pmol X ml-1) and glucagon (4 +/- 0.4 vs. 10 +/- 2 pmol X l-1) were lower (P less than 0.05) and epinephrine higher (0.30 +/- 0.06 vs. 0.09 +/- 0.03 nmol X l-1) in T than in C subjects. During and after insulin infusion production, disappearance and clearance of glucose changed identically in T and C subjects. However, in spite of identical plasma glucose concentrations, epinephrine (7.88 +/- 0.99 vs. 3.97 +/- 0.40 nmol X l-1), growth hormone (97 +/- 17 vs. 64 +/- 6 mU X l-1), and pancreatic polypeptide (361 +/- 84 vs. 180 +/- 29 pmol X l-1) reached higher levels (P less than 0.05) and glucagon (28 +/- 3 vs. 47 +/- 10 pmol X l-1) lower levels in T than in C subjects. Blood pressures changed earlier in athletes during insulin infusion, and early recovery of heart rate, free fatty acid, and glycerol was faster. Responses of norepinephrine, cortisol, C-peptide, and lactate were similar in the two groups. Training radically changes hormonal responses but not glucose kinetics in insulin hypoglycemia.

Adult↗
PubMed1981

Significance of glucagon for insulin secretion and hepatic glycogenolysis during exercise in rats.

The significance of glucagon and of the sympatho-adrenal system for insulin secretion and hepatic glycogen depletion during exercise was studied. Male rats were either adrenodemedullated and chemically sympathectomized with 6-hydroxydopamine (SX) or sham-treated (C). During light ether anesthesia, cardiac blood for glucose analysis and a biopsy of the liver were obtained, and either antigen-stripped glucagon antibodies (A) or control gamma globulins (N) in saline were injected through the cardiac cannula. Subsequently, the rats swam in tepid water (33-34 degree C) for 100 minutes with a tail weight attached (2% of body weight). Then cardiac blood was drawn for analysis of glucose, insulin and glucagon, and a sample of the liver was collected. In both CA and CN rats, the blood glucose concentration tended to increase (p less than 0.1) during exercise, whereas hepatic glycogen depletion and the plasma insulin concentration were lower in CA rats compared to CN rats. In SX rats, the blood glucose concentration did not increase during exercise, and in SXA but not in SXN rats, the hepatic glucogen depletion was lower than in CN rats. The plasma insulin concentration was consistently higher in SX rats than in C rats, and was significantly decreased by glucagon antibodies in SX as well as in C rats. In conclusion, in exercising rats, glucagon enhances hepatic glycogen depletion. Furthermore, glucagon and the sympatho-adrenal system increase and decrease, respectively, the plasma insulin concentration.

Adrenal Medulla↗
PubMed1981

[Computer angiography in renal transplants (author's transl)].

The results of computed angiography in 12 patients with renal transplants are described. In five patients with normal function of the transplant and normal appearances on a conventional angiogram, under-perfusion averaging 36% was demonstrated. In two out of three patients with a stenosis at the anastomosis, the effect of the stenosis on function could be shown. In two patients with acute rejection of the graft and hypoxia of the tubules, the differential diagnosis could be clarified by means of computer angiography. Computer angiography can therefore be regarded as a valuable addition to conventional angiography for the differentiation between tubular hypoxia and acute rejection and for underperfusion of a renal transplant.

Angiography↗
PubMed1981

Role of epinephrine for muscular glycogenolysis and pancreatic hormonal secretion in running rats.

We have previously shown that during swimming muscular glycogen breakdown was diminished and plasma glucagon and insulin were lower and higher, respectively, in adrenodemedullated rats compared to controls. These findings might be due to a lower work intensity or higher efficiency in adrenodemedullated rats than in controls. Furthermore, they might be due to either an acute or a chronic influence of epinephrine. Rats were adrenodemedullated (DM) or sham-operated (C). They were chronically cannulated and either rested or ran in a metabolism chamber for 45 min. Running DM rats had either saline (DM-S) or epinephrine (normalizing the concentration in plasma) (DM-E) infused. During running, oxygen uptake was identical in C and DM rats. Muscular glycogen breakdown was similar in DM-E and C rats and higher than in DM-S rats. Blood glucose, lactate, and heart rate increased in C and DM-E, but not in DM-S rats. In spite of the differences in blood glucose, plasma insulin was the same in all groups and plasma glucagon increased identically in all running rats. Plasma FFA and liver glycogen were similar in all groups. In conclusion. in running rats, epinephrine exerts an acute enhancing effect on muscular glycogenolysis, glucagon secretion, and heart rate and an acute depressing effect on insulin secretion.

Adrenal Medulla↗
PubMed1980

Simultaneous determinations of metabolic and hormonal responses, heart rate, temperature and oxygen uptake in running rats.

UNLABELLED: We have developed a tiny metabolism chamber, including a treadmill, for the study of exercising rats. The effects of work time, speed and inclination of running on VO2, heart rate (HR), respiratory exchange ratio (R) and rectal temperature (TR) were determined. During prolonged runnig VO2, HR, R and catecholamine concentrations in arterial plasma drawn through chronically implanted catheters displayed an initial "overshooting", which did not diminish during the four times the rats within 10 days participated in experiments. When graded exercise was performed after a pre-test run of low intensity VO2, HR, R and TR increased with increasing running speed but did not vary with inclination. During 45 min of running, the plasma concentration of glucagon increased and that of insulin remained unchanged in spite of a marked increase in blood glucose. CONCLUSIONS: In exercise studies in rats it is necessary to introduce a 20 min pre-test period, during which unspecific stress responses disappear. This pre-test period cannot be replaced by "habituation runs" on 3 preceding days. Furthermore, using rats, running speed rather than inclination has to be changed in order to establish physiologically significant differences in work intensity. The chamber makes it possible to carry out sophisticated studies of adaptations to exercise of a wide range of intensities in untrained rats and to relate the responses to VO2.

Animals↗
PubMed1980

Gastroenteropancreatic hormonal changes during exercise.

Peripheral plasma concentrations of gastroenteropancreatic peptides were measured during a 3-h period of bicycle exercise at 40% of maximal oxygen uptake in six normal men. Marked increases (P < 0.02) were found in vasoactive intestinal polypeptide (VIP) [1.8 +/- 0.7 (rest) vs. 22.3 +/- 5.4 pmol x l-1 (mean +/- SE) (3 h)], secretin (0.5 +/- 0.5 vs. 11.1 +/- 2.7 pmol x l-1), pancreatic polypeptide (PP) (4.0 +/- 1.5 vs. 46.3 +/- 11.5 pmol x l-1), somatostatin (SRIF) (12.8 +/- 1.2 vs. 17.7 +/- 0.6 pmol x l-1), whereas no changes occurred in gastric inhibitory polypeptide (37.3 +/- 5.9 vs. 39.2 +/- 9.8 pmol x l-1). Immunoreactive insulin and C-peptide decreased from 0.08 +/- 0.004 and 0.39 +/- 0.03 pmol x l-1, respectively, to 0.04 +/- 0.003 (P < 0.005) and 0.13 +/- 0.02 (P < 0.001). The significant decrease in C-peptide and in the C-peptide-to-insulin molar ratio indicate decreased insulin secretion and clearance, respectively, during exercise. Plasma glucose decreased [5.0 +/- 0.1 (rest) vs. 4.2 +/- 0.3 mmol.l-1 (3 h)] (P < 0.01). During 3 h of rest, none of the measured parameters had changed. The marked exercise-induced changes in plasma concentrations of PP, secretin, VIP, and SRIF are provocative. We know in detail neither the stimuli for the release of these peptides nor their physiological role during exercise.

Adolescent↗