Two molecular species of repressible extracellular phosphodiesterases showing cyclic 2',3'- and cyclic 3',5'-nucleotide phosphodiesterase activities were detected in mycelial culture media of wild-type Neurospora crassa and purified. The two molecular species were found to be monomeric and polymeric forms of an enzyme constituted of identical subunits having molecular weights of 50,000. This en...

The effect of calcitonin gene-related peptide (CGRP) on the cyclic nucleotide level in isolated mouse diaphragm was investigated. CGRP at concentrations of up to 1 microM caused dose-dependent increases in cyclic AMP levels but had no effect on cyclic GMP levels. At 1 microM, CGRP increased cyclic AMP levels by about 2.7-fold. Moreover, in the presence of phosphodiesterase inhibitor (Ro 20-1724...

A protein kinase has been purified from the bovine corpus luteum by acid precipitation, ammonium sulfate fractionation and chromatography on DEAE-cellulose and hydroxylapatite columns. The enzyme has a molecular weight of approximately 159,000. DEAE-cellulose chromatography resolved the protein kinase activity into two peaks, designated as KI and KII. Both peaks possessed adenosine 3’,5’-monoph...

The combined effects of cortisol and agents acting through a cyclic AMP-mediated mechanism have been studied in cultures of highly purified human peripheral lymphocytes. Incubation with prostaglandin E(1) (PGE(1)), dibutyryl cyclic AMP, or cortisol results in a concentration-dependent inhibition of [(3)H]-thymidine incorporation by both unstimulated and phytohemagglutinin (PHA)-stimulated lymph...

During growth of myxamoebae of Dictyostelium discoideum (strain Ax-2) in axenic medium, the myxamoebae secrete cyclic AMP. As the cells leave the exponential phase of growth and enter the stationary phase, there is an approximate doubling of the intracellular cyclicAMP content, but the amount ofextracellular cyclicAMP remains proportional, at all times, to the number ofmyxamoebae present. Durin...

Mutants in the cyclic AMP binding site of the cyclic AMP receptor protein (CRP) of Escherichia coli have been constructed by oligonucleotide-directed mutagenesis. They have been phenotypically characterized and their ability to enhance the expression of catabolite-repressible operons has been tested. In addition, the binding of cyclic nucleotides to the mutants has been investigated. It is show...

Vasoactive intestinal peptide (VIP) stimulated cyclic AMP production in rat peritoneal macrophages. The stimulatory effect of VIP was dependent on time, temperature and cell concentration, and was potentiated by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). At 15 degrees C, the response occurred in the 0.1-1000 nM range of VIP concentrations. Half maximal stimulation of ce...

We have previously demonstrated that a cultured porcine kidney cell, LLC-PK(1), maintains the characteristics of a polar renal epithelial cell in culture, and responds to salmon calcitonin and [arginine]vasopressin by increasing cyclic AMP content. To demonstrate the usefulness of this cell line as a model for the study of the biochemical events distal to cyclic AMP production, the activation o...

Continuous perfusion of rat hearts with concentrations of forskolin between 0.1 and 12 microM resulted in transient increases in tension after 45 s, followed by a return to the control value after 5 min. In contrast, the content of cyclic AMP increased linearly with time over this period, reaching values up to 35 times control after 5 min. Increases in contractile force, intracellular cyclic AM...

A new potent vasodilator, nicardipine hydrochloride inhibited oxytocin-induced contraction of rat uterus dose-dependently with an increase in the intracellular cyclic AMP level at the onset of relaxation. Dibutyryl cyclic AMP and papaverine, an inhibitor of cyclic AMP phosphodiesterase (PDEase), also inhibited the contraction. Nicardipine inhibited competitively PDEase in homogenates of rat ute...