scholarly journals β-adrenergic control of phosphatidylcholine synthesis by transmethylation in hepatocytes from juvenile, adult and adrenalectomized rats

1983 ◽  
Vol 216 (3) ◽  
pp. 675-680 ◽  
Author(s):  
D Marin-Cao ◽  
V Alvarez Chiva ◽  
J M Mato
Keyword(s):  
Cyclic Amp ◽  
Rat Liver ◽  
Beta Blocker ◽  
Cyclic Amp Accumulation ◽  
Adrenergic Control ◽  
Beta Receptors ◽  
Dose Dependent ◽  
Phosphatidylcholine Synthesis ◽  
Adrenalectomized Rats ◽  
Stimulation Of

Changes in isoprenaline-sensitive phospholipid methyltransferase were studied in hepatocytes isolated from juvenile, mature and adrenalectomized rats. Isoprenaline produced greater stimulation of cyclic AMP accumulation in juvenile and mature adrenalectomized rats than in mature animals. Similarly, isoprenaline stimulated phospholipid methyltransferase in juvenile and mature adrenalectomized rats but had no effect in mature animals. Isoprenaline-mediated activation of phospholipid methyltransferase in adrenalectomized rats was time- and dose-dependent. In hepatocytes isolated from adrenalectomized rats incubated with [Me-3H]methionine or [3H]-ethanolamine the addition of isoprenaline increased the amount of radioactivity incorporated into phosphatidylcholine. The activation by isoprenaline of phospholipid methyltransferase was abolished by the beta-blocker propranolol and by insulin. These results indicate that rat liver the occupation of functional beta-receptors causes a stimulation of phospholipid methylation. It is suggested that, as reported previously, cyclic AMP activates phospholipid methyltransferase.

scholarly journals Effect of adrenalectomy on acceleration of gluconeogenesis by calcium ions, adenosine 3′:5′-cyclic monophosphate and adrenaline in rat kidney tubules

1978 ◽  
Vol 174 (2) ◽  
pp. 641-646 ◽  
Author(s):  
D W R MacDonald ◽  
E D Saggerson
Keyword(s):  
Cyclic Amp ◽  
Calcium Ions ◽  
Beta Blocker ◽  
Rat Kidney ◽  
Male Rats ◽  
Kidney Tubules ◽  
Cyclic Monophosphate ◽  
Alpha Blocker ◽  
Adrenalectomized Rats ◽  
Stimulation Of

1. Gluconeogenesis from pyruvate was measured in renal-cortical-tubules fragments prepared from fed male rats 6-8 days after adrenalectomy or sham adrenalectomy. The response of this process to 3′:5′-cyclic AMP and adrenaline was compared in these two states at two Ca2+ concentrations. 2. Adrenalectomy decreased the percentage stimulation of gluconeogenesis by 3′:5′-cyclic AMP, but increased percentage stimulation by adrenaline. Cortisol treatment of adrenalectomized rats (50 mg/kg, twice daily for 2 days) did not reverse the change in responsiveness to 3′:5′-cyclic AMP and adrenaline. 3. Stimulation of gluconeogenesis by 1 micron-adrenaline was unaffected by 10 micron-propranolol (beta-blocker) in either state. Phentolamine (alpha-blocker; 10 micron) totally blocked stimulation of gluconeogenesis by 1 micron-adrenaline in the sham-operated condition, but was only partially effective in this respect after adrenalectomy.

Regulation of oxytocin secretion by the ovine corpus luteum: effect of activators of protein kinase C

1990 ◽  
Vol 124 (2) ◽  
pp. 225-232 ◽  
Author(s):  
J. J. Hirst ◽  
G. E. Rice ◽  
G. Jenkin ◽  
G. D. Thorburn
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Corpus Luteum ◽  
Phospholipase C ◽  
Tissue Slices ◽  
Kinase C ◽  
Luteal Tissue ◽  
Dose Dependent ◽  
Stimulation Of

ABSTRACT The effect of protein kinase C activation and dibutyryl cyclic AMP on oxytocin secretion by ovine luteal tissue slices was investigated. Several putative regulators of luteal oxytocin secretion were also examined. Oxytocin was secreted by luteal tissue slices at a basal rate of 234·4 ± 32·8 pmol/g per h (n = 24) during 60-min incubations.Activators of protein kinase C: phorbol 12,13-dibutyrate (n = 8), phorbol 12-myristate,13-acetate (n = 4) and 1,2-didecanoylglycerol (n = 5), caused a dose-dependent stimulation of oxytocin secretion in the presence of a calcium ionophore (A23187; 0·2 μmol/l). Phospholipase C (PLC; 50–250 units/l) also caused a dose-dependent stimulation of oxytocin secretion by luteal slices. Phospholipase C-stimulated oxytocin secretion was potentiated by the addition of an inhibitor of diacylglycerol kinase (R59 022; n = 4). These data suggest that the activation of protein kinase C has a role in the stimulation of luteal oxytocin secretion. The results are also consistent with the involvement of protein kinase C in PLC-stimulated oxytocin secretion. The cyclic AMP second messenger system does not appear to be involved in the control of oxytocin secretion by the corpus luteum. Journal of Endocrinology (1990) 124, 225–232

Cyclic nucleotides, calcium, bicarbonate, and protein secretion in canine pancreatic juice in response to cholecystokinin–pancreozymin

1979 ◽  
Vol 57 (6) ◽  
pp. 541-546 ◽  
Author(s):  
H. L. Cailla ◽  
H. Sarles ◽  
M. V. Singer
Keyword(s):  
Cyclic Amp ◽  
Pancreatic Juice ◽  
Cyclic Gmp ◽  
Cyclic Nucleotides ◽  
Parallel Increase ◽  
Calcium Bicarbonate ◽  
Strong Linear Correlation ◽  
Protein Output ◽  
Dose Dependent ◽  
Stimulation Of

The secretion of cyclic AMP, cyclic GMP, protein, calcium, and bicarbonate in the pancreatic juice of three nonanesthetized dogs with chronic gastric and duodenal Thomas cannulae has been studied. Intravenous infusions of increasing doses of cholecystokinin–pancreozymin (CCK) (1.5, 3, 6, 12, 24 Crick Harper-Raper (CHR) U kg−1 h−1) were administered together with a continuous submaximal dose of secretin (1 clinical unit (CU) kg−1 h−1). Doubling CCK doses every 45 min induced a parallel increase in the output of both cyclic nucleotides. Cyclic AMP output peaked at between 15 and 30 min for 3 and 6 U kg−1 h−1 of CCK and later for 12 and 24 U kg−1 h−1 of CCK whereas cyclic GMP output increased more constantly. Calcium output followed a pattern similar to that of cyclic GMP secretion. Flow rate and protein output attained their peaks at between 30 and 45 min. A strong linear correlation was found between the quantities of cyclic AMP, cyclic GMP, and the quantities of protein secreted in response to each CCK dose. This study demonstrates the presence of cyclic GMP in the canine pancreatic juice and the dose-dependent stimulation of the secretion of cyclic GMP and cyclic AMP by CCK in the presence of secretin.

Stimulation of T-cells with OKT3 antibodies increases forskolin binding and cyclic AMP accumulation

1990 ◽  
Vol 2 (5) ◽  
pp. 461-470 ◽  
Author(s):  
A KVANTA ◽  
P GERWINS ◽  
M JONDAL ◽  
B FREDHOLM
Keyword(s):  
T Cells ◽  
Cyclic Amp ◽  
Cyclic Amp Accumulation ◽  
Stimulation Of

Effect of histamine on canine gastric mucosal adenylate cyclase.

1977 ◽  
Vol 232 (1) ◽  
pp. E35
Author(s):  
R R Dozois ◽  
A Wollin ◽  
R D Rettmann ◽  
T P Dousa
Keyword(s):  
Gastric Mucosa ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Antral Mucosa ◽  
Fundic Mucosa ◽  
H2 Receptors ◽  
Dose Dependent ◽  
Stimulation Of

The effects of histamine, Nalpha-dimethylhistamine, 4,5-methylhistamine, Ntau-methylhistamine, pentagastrin, carbachol, and NaF on the adenylate cyclase activity from canine gastric mucosa were investigated in cell-free preparations. In gastric fundic mucosa, histamine (10(-4) M), Nalpha-dimethylhistamine (10(-4) M), 4,5-methylhistamine (10(-4 M), and NaF (10)-2) M) significantly (P less than 0.001) increased adenylate cyclase activity (means+/-SE) by 44.7+/-6.6, 49.4+/-6.7, 34.0+/-6.4, and 572.0+/-100%, respectively, above basal activity. The effect of histamine and Na-dimethyl histamine was dose-dependent. In contrast, other tested agents failed to stimulate the formation of cyclic AMP in gastric fundic mucosa. Metiamide (10(-4) M) blocked the stimulation of fundic mucosa adenylate cyclase by histamine and Nalpha-dimethylhistamine, without significantly altering basal and NaF-induced adenylate cyclase activity. Histamine, however, did not stimulate the adenylate cyclase activity from the gastric antral mucosa. The findings support the proposal that the canine gastric acid response to histamine may be mediated by cyclic AMP formed in response to stimulation of histamine H2-receptors.

scholarly journals Cross-talk between glucagon- and adenosine-mediated signalling systems in rat hepatocytes: effects on cyclic AMP-phosphodiesterase activity

1995 ◽  
Vol 312 (3) ◽  
pp. 763-767 ◽  
Author(s):  
M Robles-Flores ◽  
G Allende ◽  
E Piña ◽  
J A García-Sáinz
Keyword(s):  
Cyclic Amp ◽  
Pertussis Toxin ◽  
Plasma Membranes ◽  
Rat Hepatocytes ◽  
Dependent Manner ◽  
Phosphodiesterase Activity ◽  
Cyclic Amp Phosphodiesterase ◽  
Cyclic Amp Accumulation ◽  
A1 Adenosine Receptors ◽  
Dose Dependent

The effect of adenosine analogues on glucagon-stimulated cyclic AMP accumulation in rat hepatocytes was explored. N6-Cyclopentyladenosine (CPA), 5′-N-ethylcarboxamidoadenosine and N6-(R-phenylisopropyl)adenosine inhibited in a dose-dependent manner the cyclic AMP accumulation induced by glucagon. This effect seems to be mediated through A1 adenosine receptors. Pertussis toxin completely abolished the effect of CPA on glucagon-stimulated cyclic AMP accumulation in whole cells which suggested that a pertussis-toxin-sensitive G-protein was involved. On the other hand, this action of adenosine analogues on glucagon-induced cyclic AMP accumulation was reverted by the selective low-Km cyclic AMP-phosphodiesterase inhibitor Ro 20-1724. Analysis of cyclic AMP-phosphodiesterase activity in purified hepatocyte plasma membranes showed that glucagon in the presence of GTP inhibited basal PDE activity by 45% and that CPA reverted this inhibition in dose-dependent manner. In membranes derived from pertussis-toxin-treated rats, we observed no inhibition of cyclic AMP-phosphodiesterase activity by glucagon in the absence or presence of CPA. Our results indicate that in hepatocyte plasma membranes, stimulation of adenylate cyclase activity and inhibition of a low-Km cyclic AMP phosphodiesterase activity are co-ordinately regulated by glucagon, and that A1 adenosine receptors can inhibit glucagon-stimulated cyclic AMP accumulation by blocking glucagon's effect on phosphodiesterase activity.

Sign in / Sign up

Export Citation Format

Share Document