scholarly journals 3,3′,5-Triiodothyronine Administration In Vivo Modulates the Hormone-sensitive Adenylate Cyclase System of Rat Hepatocytes

1982 ◽  
Vol 69 (2) ◽  
pp. 414-426 ◽  
Author(s):  
Craig C. Malbon ◽  
Michael L. Greenberg
Keyword(s):  
Adenylate Cyclase ◽  
Rat Hepatocytes ◽  
Adenylate Cyclase System ◽  
Hormone Sensitive

Effects of benzyl alcohol on PTH receptor-adenylate cyclase system of canine kidney

1985 ◽  
Vol 248 (1) ◽  
pp. E31-E35
Author(s):  
K. J. Martin ◽  
C. L. McConkey ◽  
T. J. Stokes
Keyword(s):  
Enzyme Activity ◽  
Adenylate Cyclase ◽  
Benzyl Alcohol ◽  
Membrane Fluidity ◽  
Phospholipid Composition ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Adenylate Cyclase System ◽  
Hormone Sensitive ◽  
Canine Kidney

In many systems, perturbations of membrane architecture by changes of lipid and phospholipid composition have been shown to alter the activity of membrane-bound enzymes. The present studies examined the effect of benzyl alcohol, an agent that has been shown to increase membrane fluidity, on the parathyroid hormone (PTH)-sensitive adenylate cyclase system of canine kidney. Benzyl alcohol progressively increased basal adenylate cyclase activity up to fourfold and maximal enzyme activity in the presence of PTH, GTP, guanylimidodiphosphate, and sodium fluoride by four- to sixfold. In the presence of 20 mM Mn2+ (no Mg2+), conditions under which enzyme activity is devoid of influence of guanine nucleotides or hormones, benzyl alcohol was without effect. PTH binding was increased by 25% in the presence of benzyl alcohol without a change in binding affinity. Fluorescent polarization studies using diphenylhexatriene showed a decrease in fluorescence anisotropy in the presence of benzyl alcohol. The results suggest that benzyl alcohol facilitates the interaction of the components of the adenylate cyclase system, presumably by increasing membrane fluidity. Alterations of membrane fluidity may be a potent means of regulating hormone sensitive adenylate cyclase activity.

Acetylcholine and norepinephrine interactions on cardiac lipids and hemodynamics

1975 ◽  
Vol 228 (6) ◽  
pp. 1678-1684 ◽  
Author(s):  
VV Glaviano ◽  
J Goldberg ◽  
MT Pindok
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Lipolytic Activity ◽  
Cardiac Metabolism ◽  
Left Ventricular ◽  
Extraction Ratio ◽  
Adenylate Cyclase System ◽  
Sodium Pentobarbital ◽  
Myocardial Uptake ◽  
Hormone Sensitive

In open-chest dogs anesthized with sodium pentobarbital, acetylcholine (ACh, 5 times 10'-5M) infused into the left circumflex coronary artery caused an increase in coronary flow and a decrease in myocardial O'2 extraction ratio (P less than .01) anduptake (P less than .05). Heart rate and mean arterial pressure were not altered,although left ventricular dP/dt declined from 2,037 plus or minus 205 to 1,873 plus or minus 194 mmHg/s (P less than .02). Intracoronary administration of norepinephrine (NE, 2.4 times 10'-6M) caused an increase in myocardial O'2 uptake (P less than .02); simultaneous infusion of both NE and ACh caused a decline in O'2 extraction ratio (P less than .01) and uptake (P less than 0.5). Myocardial adenylatecyclase activity in response to ACh was not altered significantly from a control levelof 188 plus or minus 22 pmol of '14C-labeled cyclic AMP/mg protein per 10 min. Norepinephrine alone elevated adenylate cyclase activity to 401 plus or minus 45 pmol ['14C]cyclic AMP/mg protein per 10 min (P less than .01). However, with simultaneous infusion of both NE and ACh, adenylate cyclase returned to control levels. Although ACh alone did not alter myocardial hormone-sensitive lipaseactivity, NE elevated lipolytic activity from 8.1 plus or minus .7 to 13.2 plus or minus 1.8 mueq free fatty acid (FTA)/g per 30 min (P less than .05). The administration of both ACh and NE returned lipase activity to nearly control levels. Myocardial uptake of FFA increased significantly during ACh infusion alone (P less than 0.5) and during NE infusion alone (P less than 905). However, when NE and AChwere administered together, a decline in FFA uptake was observed (P less than .02).These data indicate that the effects of ACh on cardiac metabolism are minimal, withthe decline in myocardial O'2 uptake of ACh primarily reflecting the decrease in contractility. On the other hand, antagonism of ACh on NE-stimulated myocardial lipid metabolism appears to involve activity of the adenylate cyclase system.

Desensitization of the ?-adrenoceptor-adenylate cyclase system of immature erythrocytes by in-vivo treatment of rats with isoprenaline

1981 ◽  
Vol 317 (4) ◽  
pp. 294-301 ◽  
Author(s):  
G. Wiemer ◽  
G. Kaiser ◽  
J. Dietz ◽  
M. Reinhardt ◽  
A. Wellstein ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Adenylate Cyclase System ◽  
In Vivo Treatment

Changes in skeletal muscle glycogenolysis after prolonged cold exposure and repeated injections with isoproterenol

1979 ◽  
Vol 57 (9) ◽  
pp. 938-943 ◽  
Author(s):  
M. C. Thibault ◽  
C. Côté ◽  
J. Vallières
Keyword(s):  
Adenylate Cyclase ◽  
Cold Stress ◽  
Tibialis Anterior ◽  
Skeletal Muscles ◽  
Glycogen Phosphorylase ◽  
Phosphorylase Kinase ◽  
Adenylate Cyclase System ◽  
Great Capacity ◽  
Contracting Muscle

Wistar rats were either given daily injections of isoproterenol (ISO) (15 μg/100 g per day) or exposed to 6 °C for 4 or 12 weeks (cold acclimated (CA)). After a 4-week exposure to cold and to ISO, acute cold stress (4 h at –18 °C) produced a 48% depletion of glycogen in the tibialis anterior of control rats while it did not significantly affect the levels in ISO-treated and CA animals. ISO treatment enhanced the in vivo response of phosphorylase kinase and glycogen phosphorylase to epinephrine (EPI) in the tibialis anterior, a fast contracting muscle. In the soleus, a slow contracting muscle known to be more sensitive to catecholamines, chronic treatment with ISO also resulted in increased basal and EPI-stimulated adenylate cyclase activity. No evidence could be found for an alteration of the glycogenolytic pathway (adenylate cyclase system, phosphorylase kinase, and glycogen phosphorylase) in fast contracting skeletal muscles of CA rats. It is concluded that ISO-treated and CA rats, which have a great capacity for nonshivering thermogenesis, do not rely on their muscle carbohydrate reserves during cold stress. It might be suggested that plasma levels of catecholamines higher than those produced by exposure to 6 °C are required to alter glycogenolytic mechanisms in fast contracting rat skeletal muscles.

Control of adipose tissue lipolysis in ectotherm vertebrates

1992 ◽  
Vol 263 (4) ◽  
pp. R857-R862 ◽  
Author(s):  
R. H. Migliorini ◽  
J. S. Lima-Verde ◽  
C. R. Machado ◽  
G. M. Cardona ◽  
M. A. Garofalo ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Adenylate Cyclase ◽  
Lipolytic Activity ◽  
Adenylate Cyclase System ◽  
Triacylglycerol Lipase ◽  
Membrane Bound ◽  
Adipose Tissue Lipolysis ◽  
Toad Bufo

Lipolytic activity of fish (Hoplias malabaricus), toad (Bufo paracnemis), and snake (Philodryas patagoniensis) adipose tissue was investigated in vivo and in vitro. Catecholamines or glucagon did not affect the release of free fatty acids (FFA) by incubated fish and toad adipose tissue. Catecholamines also failed to activate snake adipose tissue lipolysis, which even decreased in the presence of epinephrine. However, glucagon stimulated both the lipolytic activity of reptilian tissue in vitro and the mobilization of FFA to plasma when administered to snakes in vivo. The release of FFA from incubated fish, amphibian, and reptilian adipose tissue increased markedly in the presence of cAMP or xanthine derivatives, inhibitors of phosphodiesterase. Forskolin or fluoride, activators of specific components of the adenylate cyclase system, strongly stimulated toad adipose tissue lipolysis. The data suggest that adipocyte triacylglycerol lipase of ectotherm vertebrates is activated by a cAMP-mediated phosphorylation and that the organization of the membrane-bound adenylate cyclase system is similar to that of mammals.

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