3′:5′-Cyclic-AMP Phosphodiesterase Activities in White and Brown Adipose Tissues of Cold-Acclimated Rats

1975 ◽  
Vol 53 (12) ◽  
pp. 1301-1308 ◽  
Author(s):  
R. Bertin ◽  
R. Portet
Keyword(s):  
Adipose Tissue ◽  
Cyclic Amp ◽  
Specific Activity ◽  
Epididymal Adipose Tissue ◽  
Interscapular Brown Adipose Tissue ◽  
Cyclic Amp Phosphodiesterase ◽  
High K ◽  
Brown Adipose ◽  
Tissue Homogenates ◽  
Low K

3′:5′-Cyclic-AMP phosphodiesterase (PDE) (EC 3.1.4.17) activity was measured in interscapular brown adipose tissue (BAT) and in white epididymal adipose tissue of rats acclimated to constant or fluctuating cold. Experiments were carried out on isolated adipocytes or tissue homogenates. In brown or white adipose tissue or isolated adipocyte homogenates, two different apparent Km values were found according to the substrate (cAMP) concentration. The low Km was at about 10−6 M and the high one at about 10−4 M. The apparent V of the high Km enzyme was about 10-fold higher than the V of the low Km enzyme. Cold acclimation to constant or fluctuating cold did not modify appreciably the Km or V values. For low substrate concentrations (10−6–10−8 M), the specific activity of PDE expressed per milligram of protein was decreased in BAT adipocytes of the two groups of cold-acclimated rats, compared to controls. Inversely, it was increased in total tissue homogenates. These variations were smaller in fluctuating cold than in constant cold-acclimated rats. They could, in part, induce the increases in lipolysis and in blood flow observed in the BAT of cold-acclimated rats.

Abnormal brown adipose tissue in hamsters with muscular dystrophy

1980 ◽  
Vol 239 (1) ◽  
pp. C18-C22 ◽  
Author(s):  
J. Himms-Hagen ◽  
C. Gwilliam
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Cytochrome Oxidase ◽  
Specific Activity ◽  
Purine Nucleotides ◽  
Interscapular Brown Adipose Tissue ◽  
Cardiomyopathic Hamster ◽  
Brown Adipose ◽  
Cardiomyopathic Hamsters ◽  
Wet Weight

The size (wet weight, total protein, total cytochrome oxidase) of interscapular brown adipose tissue is reduced to about one-half of normal in the cardiomyopathic hamster (BIO 14.6). The mitochondria are normal in binding of purine nucleotides [guanosine 5'-diphosphate (GDP)] and in proportion of polypeptides in the region of 32,000, both indices of the thermogenic proton conductance pathway, and in specific activity of cytochrome oxidase. Brown adipose tissue of the cardiomyopathic hamster can grow during acclimation to 4 degrees C, but its size remains smaller than in cold-acclimated normal hamsters. Mitochondrial polypeptide composition is not altered by acclimation to cold, but a large increase in mitochondrial GDP binding occurs in both normal and cardiomyopathic hamsters. The reduced calorigenic response of cardiomyopathic hamsters to catecholamines (Horwitz, B.A., and G.E. Hanes, Proc. Soc. Exp. Biol. Med. 147: 393-395, 1974) may, at least in part, be explained by a reduction in the amount of brown adipose tissue, the major site of this response. A defect in control of growth of this tissue in the cardiomyopathic hamster is suggested.

Increased sympathetic activity in rat white adipose tissue during prolonged fasting

1997 ◽  
Vol 272 (2) ◽  
pp. R656-R661 ◽  
Author(s):  
R. H. Migliorini ◽  
M. A. Garofalo ◽  
I. C. Kettelhut
Keyword(s):  
Adipose Tissue ◽  
White Adipose Tissue ◽  
Sympathetic Activity ◽  
Epididymal Adipose Tissue ◽  
Turnover Rates ◽  
Prolonged Fasting ◽  
Interscapular Brown Adipose Tissue ◽  
Brown Adipose ◽  
6 Hydroxydopamine ◽  
Fasted Rats

The effect of prolonged fasting on sympathetic activity was examined in rat white adipose tissue (WAT) and, for comparison purposes, in interscapular brown adipose tissue (IBAT). Preliminary experiments showed that 6-hydroxydopamine or tyramine administration to fed animals produced similar reductions in norepinephrine (NE) content of WAT and IBAT. Fasting for 48 h did not affect tissue NE content significantly, but induced a threefold increase in [3H]NE uptake by retroperitoneal and epididymal adipose tissue, contrasting with a 50% reduction in IBAT. Measured with DL-alpha-methyl-p-tyrosine, NE fractional rates of turnover were faster and calculated turnover rates were three times higher in retroperitoneal and epididymal tissue from fasted rats than in tissues from fed controls. In experiments with [3H]NE, although fractional rates did not change significantly, calculated NE turnover also increased in retroperitoneal and epididymal tissue after food deprivation. In contrast, in IBAT, NE turnover either did not change (measured with DL-alpha-methyl-p-tyrosine) or, in the experiments with [3H]NE, decreased significantly after fasting. These and other data suggest that a centrally controlled selective activation of WAT sympathetic fibers contributes to fasting lipolysis.

scholarly journals A protein kinase inhibitor in brown adipose tissue of developing rats

1974 ◽  
Vol 138 (2) ◽  
pp. 195-199 ◽  
Author(s):  
Josef P. Skala ◽  
George I. Drummond ◽  
Peter Hahn
Keyword(s):  
Adipose Tissue ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Brown Adipose Tissue ◽  
Inhibitory Activity ◽  
Kinase Inhibitor ◽  
Protein Kinase Inhibitor ◽  
Supernatant Fraction ◽  
Brown Adipose ◽  
Tissue Homogenates

A heat-stable protein was extracted from brown adipose tissue of infant rats that inhibited both purified bovine heart protein kinase and a crude preparation of protein kinase from brown fat. It did not act as an adenosine triphosphatase nor did it exert its effect by proteolytic action. Inhibition of protein kinase was affected in both the presence and the absence of cyclic AMP. Most of the inhibitory activity was present in the 100000g supernatant fraction of tissue homogenates. Inhibitory activity was highest perinatally and it declined 10 days after birth. It is suggested that the protein kinase inhibitor may play a role in regulating cyclic AMP actions.

Potentiation of in vivo thermogenesis in rat brown adipose tissue by stimulation of α1-adrenoreceptors is associated with increased release of cyclic AMP

1984 ◽  
Vol 62 (8) ◽  
pp. 943-948 ◽  
Author(s):  
Stephanie W. Y. Ma ◽  
David O. Foster
Keyword(s):  
Adipose Tissue ◽  
Cyclic Amp ◽  
Brown Adipose Tissue ◽  
Interscapular Brown Adipose Tissue ◽  
Brown Adipose ◽  
Plasma Camp ◽  
Na Release ◽  
Stimulation Of ◽  
Thermogenic Response

Release of cyclic AMP (cAMP) from the interscapular brown adipose tissue (IBAT) of barbital-anesthetized, cold-acclimated rats given activators and inhibitors of brown adipose tissue (BAT) thermogenesis was assessed by measuring IBAT blood flow (microsphere method) and the arteriovenous difference in plasma cAMP across the tissue. The release was taken as an index of the generation of cAMP in the IBAT. During thermogenesis induced by infusion of graded doses of noradrenaline (NA), release of cAMP increased from no significant release without NA to 68 pmol/min at a NA dose that effected maximal thermogenesis. The α-adrenoreceptor antagonist dihydroergotoxin inhibited NA-induced BAT thermogenesis and markedly reduced the release of cAMP. The α1-adrenoreceptor agonist phenylephrine potentiated the in vivo thermogenic response of BAT to isoproterenol or to a suboptimal dose of NA and enhanced the release of cAMP elicited by these catecholamines. But given alone, phenylephrine or dihydroergotoxin had very little or no effect on thermogenesis and cAMP release. These results suggest that stimulation of the α1-adrenoreceptors on BAT adipocytes potentiates the thermogenic response originating from stimulation of the adenylate cyclase-coupled β1-adrenoreceptors by increasing, in some indirect way, the generation of cAMP, the intracellular messenger for activation of thermogenesis. However, in the absence of proof that adipocytes are the principal source of the cAMP released from IBAT, during catecholamine-induced thermogenesis, this explanation for the effect of α1-adrenoreceptor stimulation on thermogenesis remains tentative.

Changes in the Amount and Properties of Adenyl Cyclase in Brown Adipose Tissue during Acclimation of Rats to Cold

1971 ◽  
Vol 49 (7) ◽  
pp. 802-810 ◽  
Author(s):  
Michelle Muirhead ◽  
Jean Himms-Hagen
Keyword(s):  
Adipose Tissue ◽  
Cell Membrane ◽  
Brown Adipose Tissue ◽  
Specific Activity ◽  
Adenyl Cyclase ◽  
Cyclase Activity ◽  
Adenyl Cyclase Activity ◽  
Interscapular Brown Adipose Tissue ◽  
Exposure To Cold ◽  
Brown Adipose

Adenyl cyclase of interscapular brown adipose tissue of rats undergoing acclimation to cold was measured in order to find out whether the amount of the nor adrenaline-stimulated enzyme might be increased in cold-acclimated rats, in which a characteristic large increase in the overall calorigenic response to noradrenaline (nonshivering thermogenesis) is induced by the prolonged exposure to cold (4–8 weeks). It was found that the growth of the brown adipose tissue in the acclimating rats is accompanied by an increase in the total amount of noradrenaline-stimulated adenyl cyclase activity. Since this increase does not keep pace with the growth of the tissue a reduction in specific activity of the noradrenaline-stimulated adenyl cyclase was observed. Thus no evidence was obtained for an increased concentration of noradrenaline-responsive structures in the cell membrane of the brown adipose tissue of cold-acclimated rats.In contrast, fluoride-stimulated adenyl cyclase activity increased almost twofold after only 2 days of exposure to cold and before the growth of the tissue had started. Thereafter the activity of this enzyme increased in parallel to the growth of the tissue. The extra activity that developed during the first 2 days persisted throughout the period of acclimation to cold (8 weeks); it disappeared within 1 day when the cold-acclimated rats were returned to room temperature.These changes in adenyl cyclase activity are more rapid than any hitherto reported. They presumably reflected a change in the properties of the cell membrane in response to an environmental stress. It is not known whether the increase in measurable fluoride-stimulated adenyl cyclase activity reflects an increase in the synthesis of a specific protein or an unmasking of the activity of an enzyme already present.No change in the specific activity of cyclic AMP phosphodiesterase was observed; during acclimation to cold the total amount of this enzyme increased in parallel with the growth of the tissue.

scholarly journals Persistence of the effect of insulin on pyruvate dehydrogenase activity in rat white and brown adipose tissue during the preparation and subsequent incubation of mitochondria

1984 ◽  
Vol 217 (2) ◽  
pp. 441-452 ◽  
Author(s):  
R M Denton ◽  
J G McCormack ◽  
S E Marshall
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Dehydrogenase Activity ◽  
Pyruvate Dehydrogenase ◽  
Plasma Membranes ◽  
Pyruvate Dehydrogenase Kinase ◽  
Epididymal Adipose Tissue ◽  
Short Term ◽  
Interscapular Brown Adipose Tissue ◽  
Brown Adipose

Increases in the amount of the active non-phosphorylated form of pyruvate dehydrogenase in rat epididymal adipose tissue, as a result of incubation with insulin, persist not only during the preparation of mitochondria but also during subsequent incubation of coupled mitochondria in the presence of respiratory substrates. No effect on insulin was found if the hormone was added directly to mitochondria in the presence or absence of added plasma membranes. Concentrations of several possible regulators of pyruvate dehydrogenase kinase (ATP, ADP, NADH, NAD+, acetyl-CoA, CoA and potassium) were measured in rat epididymal-adipose-tissue mitochondria incubated under conditions where differences in pyruvate dehydrogenase activity persist as a result of insulin action. No alterations were found, and it is suggested that inhibition of the kinase is not the principal means by which insulin activates pyruvate dehydrogenase. The intramitochondrial concentration of magnesium was also unaffected. Differences in pyruvate dehydrogenase activity in interscapular brown adipose tissue associated with manipulation of plasma insulin concentrations of cold-adapted rats were also shown to persist during the preparation and subsequent incubation of mitochondria in the presence or absence of GDP. It is pointed out that the persistence of the effect of insulin on pyruvate dehydrogenase in incubated mitochondria will facilitate the recognition of the mechanism of this action of the hormone. Evidence that the short-term action of insulin involves an increase in pyruvate dehydrogenase phosphate phosphatase activity rather than inhibition of that of pyruvate dehydrogenase kinase is discussed.

Increased response of adipose tissue of the ob/ob mouse to the action of adrenaline after treatment with thyroxin

1977 ◽  
Vol 55 (6) ◽  
pp. 1320-1329 ◽  
Author(s):  
N. Bégin-Heick ◽  
H. M. C. Heick
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Fatty Acid ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Epididymal Adipose Tissue ◽  
Lipolytic System ◽  
Low K ◽  
Fatty Acid Mobilization

The activity of the lipolytic system of the obese hyperglycemic mouse was assessed after treatment with physiological doses of thyroxin (T4). The treatment significantly increased fatty acid mobilization in response to adrenaline over the levels observed in the control mice under all conditions studied. The activities of the high- and low-Km phosphodiesterases and of adenylate cyclase were also studied. Treatment of the ob/ob mice with T4 had little effect on the activities of the cyclic AMP phosphodiesterases (high and low Km) but it partially restored the activity of adenylate cyclase, which is deficient in these animals. A correlation was found in the T4-treated obese animals between the ability of the epididymal adipose tissue to mobilize fatty acids, its ability to increase the intracellular levels of cyclic AMP, and the activity of adenylate cyclase in response to adrenaline stimulation.

Sign in / Sign up

Export Citation Format

Share Document