Relaxation of the guinea-pig tracheal chain preparation by N6,2'-O-dibutyryl 3',5'-cyclic adenosine monophosphate

N 6,2′-O-Dibutyryl 3′,5′-cyclic adenosine monophosphate (dibutyryl 3′,5′-amp), isoprenaline and theophylline relax the guinea-pig tracheal chain preparation; whereas 3′,5′-cyclic adenosine monophosphate (3′,5′-amp) does not. The relaxant effect of isoprenaline, but not that of dibutyryl 3′,5′-amp, was blocked by propranolol. 3′,5′-amp is hydrolyzed rapidly by beef heart phosphodiesterase whereas dibutyryl 3′,5′-amp is not. The presence of equimolar concentrations of dibutyryl 3′,5′-amp does not alter the rate of phosphodiesterase mediated hydrolysis of 3′,5′-amp. These data are consistent with the theories that relaxation of the guinea-pig trachea may be mediated by 3′,5′-amp and that dibutyryl 3′,5′-amp acts by mimicking 3′,5′-amp at its site of action.

Induction of polyomavirus DNA replication by cyclic AMP and a tumor promoter

The effects of reagents that stimulate the intracellular level of cyclic AMP (cAMP), and of a tumor promoter, on polyomavirus (Py) DNA replication were examined in a Py-transformed rat cell line, designated the LPT line. cAMP-stimulating reagents (forskolin and 3-isobutyl-1-methyl xanthine) were found to induce replication of Py DNA in normally growing LPT cells and to enhance replication of the viral DNA in cells exposed to suboptimal doses of UV light and mitomycin C (which have been previously shown to induce Py DNA replication in LPT cells). The tumor promoter 12-O-tetradecanoyl phorbol-13-acetate did not cause a significant induction in Py DNA replication when it was applied to the cells alone, but enhanced replication of the viral DNA when it was applied together with the cAMP-stimulating reagents. Cycloheximide, an inhibitor of protein synthesis, was found to inhibit the induction of Py DNA replication by the cAMP-stimulating reagents. Based on these data, and on previous studies of the Py enhancer, it is proposed that cAMP may induce synthesis of an enhancer-binding protein that causes Py DNA replication in LPT cells by binding and activating an enhancer element which is a component of the Py origin.

Cyclic nucleotide levels of nasal secretions in allergic patients and control subjects

Cyclic nucleotides (CND) levels of nasal secretions were studied in allergic rhinitis patients and control subjects. In methacholine-induced nasal secretion, allergic rhinitis patients had lower cAMP levels, higher cGMP levels and a lower cAMP/cGMP ratio than the control subjects. A close relationship was found between CND levels and the severity of daily symptoms in both methacholine-induced and antigen-induced nasal secretions.

Characterization of cpd-1 and cpd-2 mutants which affect the activity of orthophosphate regulated cyclic phosphodiesterase in Neurospora

Enzymatic and genetic characterization of cpd-1 and cpd-2, which exhibit rhythmic conidiation in liquid media and on solid media, were described with band (bd) strain as a reference. Cpd-1 and cpd-2 showed reduced growth in orthophosphate-free cyclic 3',5'-AMP media, while bd showed wild-type level of growth in the media. In low-phosphate media, cpd-1 and cpd-2 produced 19.2% and 9.8% of orthophosphate-regulated cyclic phosphodiesterase (cPDase) in culture media, while bd produced 123%. The intracellular levels of cPDase with Km of 1 x 10(-5) M in high-phosphate media in cpd-1, cpd-2 and bd were about 20%, 15%, and 10% of that in wild-type, respectively. In low-phosphate media roughly equal levels of cPDase with Km of 1 x 10(-5) M were produced in all strains, whereas the production of cPDase with Km of 2 x 10(-3) M was reduced in cpd-2, and that of cPDase with Km of 1 x 10(-2) was reduced in cpd-1 and cpd-2. The levels of intracellular cyclic 3',5'-AMP in cpd-1, cpd-2, and bd in high-phosphate media were 13.1%, 10.1%, and 69.6% of that in wild-type. Adenylate cyclase activity in cpd-1, cpd-2, bd, and cr-1 was 69.3%, 34.0%, 63.2%, and 20.3% of that of wild-type (74A). The levels of Mg++-stimulated cyclic phosphodiesterase in cpd-1, cpd-2, bd, and cr-1 at 0.2 microM cyclic 3',5'-AMP were 199%, 137%, 329%, and 293% of that of wild-type.(ABSTRACT TRUNCATED AT 250 WORDS)