Effect of NAD, nicotinamide and nicotinic acid on cyclic AMP accumulation by fat cells

1979 ◽  
Vol 306 (2) ◽  
pp. 179-183 ◽  
Author(s):  
Francisco J. Moreno ◽  
Raymond E. Shepherd ◽  
John N. Fain
Keyword(s):  
Cyclic Amp ◽  
Nicotinic Acid ◽  
Fat Cells ◽  
Cyclic Amp Accumulation

scholarly journals Attenuated adenosine-sensitivity and decreased adenosine-receptor number in adipocyte plasma membranes in human obesity

1991 ◽  
Vol 279 (1) ◽  
pp. 17-22 ◽  
Author(s):  
J M Kaartinen ◽  
S P Hreniuk ◽  
L F Martin ◽  
S Ranta ◽  
K F LaNoue ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Adenosine Receptors ◽  
Plasma Membranes ◽  
Normal Weight ◽  
Fat Cells ◽  
Cyclic Amp Accumulation ◽  
Obese Subjects ◽  
Receptor Number

Fat-cells were isolated from patients of body-mass indices (BMIs) ranging from 17.9 to 83.9 kg/m2. Isoprenaline-stimulated cyclic AMP accumulation in cells prepared from obese subjects as compared with normal-weight subjects, was less sensitive to inhibition by the adenosine agonist N6-(phenylisopropyl)adenosine (PIA) (P = 0.047). The inhibition of 7 beta-desacetyl-7 beta-[gamma-(N-methylpiperazino) butyryl]-forskolin-stimulated adenylate cyclase by PIA in the presence of adenosine deaminase was also much attenuated in crude plasma membranes of adipocytes prepared from massively obese patients as compared with lean controls (P = 0.0143). This difference was probably not due to different cell size, because adenylate cyclase of crude plasma membranes of large adipocytes was actually more sensitive to PIA than was adenylate cyclase of membranes of smaller fat-cells co-isolated from the same individual. The stimulatory effect of PIA on glucose uptake in the presence of adenosine deaminase was depressed in adipocytes prepared from obese subjects and correlated with BMI at r = -0.626 (P = 0.007) at 100 nM-PIA. The adenosine receptors were studied by using the adenosine antagonist 1,3-[3H]dipropyl-8-cyclopentylxanthine. The binding was rapid and proportional to protein concentration. There was no difference in the affinities of receptors in membranes of obese and normal-weight subjects; Kd values of all patients averaged 3.3 nM. Bmax values were 54 and 130 fmol/mg of protein in membranes prepared from seven obese and five control patients respectively. The Bmax values calculated per mg of protein correlated with BMI at r = -0.539 (P = 0.047). The adenosine content of adipose tissue was higher in obese than in control subjects. These results demonstrate an attenuated response of cyclic AMP accumulation, adenylate cyclase and glucose uptake to adenosine in fat-cells prepared from obese subjects, and suggest that this change is at least partly due to changes in the amount of adenosine receptors, but not their affinity. The decreased receptor number could be due to higher adenosine content. A higher adenosine concentration in adipose tissue could explain why lipolysis is inhibited in situ in obesity, and the desensitization could explain the diminished response to adenosine analogues in isolated fat-cells.

scholarly journals Rat fat-cells have three types of adenosine receptors (Ra, Ri and P). Differential effects of pertussis toxin

1985 ◽  
Vol 232 (2) ◽  
pp. 439-443 ◽  
Author(s):  
J A García-Sáinz ◽  
M L Torner
Keyword(s):  
Cyclic Amp ◽  
Adenosine Deaminase ◽  
Pertussis Toxin ◽  
Adenosine Receptors ◽  
Fat Cells ◽  
Differential Effects ◽  
Cyclic Amp Accumulation ◽  
Selective Agonists ◽  
Rat Fat Cells ◽  
In Cells

Activation of rat adipocyte R1 adenosine receptors by phenylisopropyladenosine (PIA) decreased cyclic AMP and lipolysis; this effect was blocked in cells from pertussis-toxin-treated rats. In contrast, the ability of 2′,5′-dideoxyadenosine to decrease cyclic AMP was not affected by pertussis-toxin treatment. Addition of adenosine deaminase to the medium in which adipocytes from control animals were incubated resulted in activation of lipolysis. Interestingly, adipocytes from toxin-treated rats (which had an already increased basal lipolysis) responded in an opposite fashion to the addition of adenosine deaminase, i.e. the enzyme decreased lipolysis, which suggested that adenosine might be increasing lipolysis in these cells. Studies with the selective agonists N-ethylcarboxamidoadenosine (NECA) and PIA indicated that adenosine increases lipolysis and cyclic AMP accumulation in these cells and that these actions are mediated through Ra adenosine receptors. Adenosine-mediated accumulation of cyclic AMP was also observed in cells preincubated with pertussis toxin (2 micrograms/ml) for 3 h. In these studies NECA was also more effective than PIA. Our results indicate that there are three types of adenosine receptors in fat-cells, whose actions are affected differently by pertussis toxin, i.e. Ri-mediated actions are abolished, Ra-mediated actions are revealed and P-mediated actions are not affected.

Lipolysis and cyclic AMP accumulation in isolated fat cells from chicks

1975 ◽  
Vol 26 (2) ◽  
pp. 243-247 ◽  
Author(s):  
Thomas A. Boyd ◽  
Paul B. Wieser ◽  
John N. Fain
Keyword(s):  
Cyclic Amp ◽  
Fat Cells ◽  
Isolated Fat Cells ◽  
Cyclic Amp Accumulation

Prostaglandin inhibition of cyclic-AMP accumulation and rate of lipolysis in fat cells

1974 ◽  
Vol 7 (4) ◽  
pp. 319-326 ◽  
Author(s):  
Colin Dalton ◽  
Harriet Hope ◽  
Loraine Martikes
Keyword(s):  
Cyclic Amp ◽  
Fat Cells ◽  
Cyclic Amp Accumulation
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