Cyclic adenosine 3’,5’-monophosphate (cyclic AMP) accumulates in guinea pig cerebral cortical slices during incubations with histamine, histamine-norepinephrine, adenosine, adenosine-histamine, adenosine-norepinephrine, adenosinehistamine-norepinephrine, veratridine, and veratridine-histamine. The rate of increase of cyclic AMP levels in response to various agents appears to be limited to some ...

Tyrosine hydroxylase, the rate-limiting enzyme in catecholamine biosynthesis, is subject to regulation by a variety of agents. Previous workers have found that cyclic AMP-dependent protein kinase and calcium-stimulated protein kinases activate tyrosine hydroxylase. We wanted to determine whether cyclic GMP might also be involved in the regulation of tyrosine hydroxylase activity. We found that ...

The capacity of allosensitized thymus-derived lymphocytes to destroy target cells bearing donor alloantigens is modulated by the cellular levels of cyclic AMP and cyclic GMP. Increases in the cyclic AMP levels of attacking lymphocytes by stimulation with prostaglandin E(1), isoproterenol, and cholera toxin inhibit lymphocyte-mediated cytotoxicity; whereas, depletion of cyclic AMP with imidazole...

A number of investigations have implied in recent years that a relationship exists between adenosine 3', 5'-cyclic monophosphate (cyclic AMP) and the growth of cells . Numerous experimental systems have been used to examine several different cell types. The result has been some definitive information about how cells divide, what role cyclic AMP plays in cell replication, and which periods of th...

A protein kinase activated by cyclic nucleotides was purified from beef heart. Upon exposure to adenosine 3':5'-cyclic monophosphate (cyclic AMP) during gel filtration on Sephadex G-200, the protein kinase dissociated into a cyclic nucleotide-independent protein kinase and a cyclic nucleotide-binding protein. A similar or identical cyclic nucleotide-independent protein kinase could be obtained ...

The dual regulation of cyclic AMP levels in rat peritoneal macrophages incubated with somatostatin, vasoactive intestinal peptide (VIP), and isoproterenol was studied. Somatostatin exerted a non-competitive inhibition of the stimulatory effect of VIP and isoproterenol on cyclic AMP production. In addition, somatostatin inhibited basal cyclic AMP levels. Our results suggest that somatostatin and...

1. The ability of exogenously administered cyclic AMP (adenosine 3': 5'-monophosphate) to exert andromimetic action on certain carbohydrate-metabolizing enzymes was investigated in the rat prostate gland and seminal vesicles. 2. Cyclic AMP, when injected concurrently with theophylline, produced marked increases in hexokinase, phosphofructokinase, glyceraldehyde phosphate dehydrogenase, pyruvate...

Amoebae of Dictyostelium discoideum show adaptation towards a chemotactic cyclic AMP signal. Within a few seconds of receipt of the signal they are inhibited for a period of 1-2 min from further chemotactic responses to subsequent cyclic AMP signals of similar or smaller magnitude. The site of this adaptation mechanism in the chemotactic transduction pathway was investigated by addition of comp...

A 2.5-fold stimulation of cyclic AMP cellular content is measured 60 sec after addition of 100 nM synthetic ovine corticotropin-releasing factor (C-RF; corticoliberin) to rat anterior pituitary cells in culture. A maximal response of cyclic AMP content at 400% above control is observed between 2 and 30 min after addition of the peptide, whereas an 8-fold stimulation of cyclic AMP released into ...

The action of prostaglandins on cyclic AMP levels in rat epididymal fat pads, isolated fat cells, and other tissues was studied. Fat pads incubated with prostaglandin El (PGE1) contained higher levels of cyclic AMP than controls but lipolysis was not stimulated. However, PGEr did not cause increased cyclic AMP levels in isolated fat cells, suggesting that the stimulatory action occurred in anot...