Objective: Does carbachol (CCh) require NO/cGMP for inhibition of L-type calcium current (I ) when either adenylyl cyclase Ca(L) activation or phosphodiesterase suppression is used to raise cAMP? Methods: The effects of the NO donor SIN-1 (3-morpholinosydnonimine), CCh and atrial natriuretic peptide (ANP) were evaluated when I had been stimulated by isoproterenol (ISO) or Ca(L) 3-isobutyl-1-met...

Competent larvae of the serpulid polychaete, Hydroides elegans (Haswell), were induced to 24 metamorphose by either 10 M 3-isobutyl 1-methylxanthine (IBMX), adult homogenate, or 30 1 1 mM excess K . Treatment with excess K had adverse effects (P , 0.05) on juvenile growth while IBMX and adult homogenate had no detectable effects (P . 0.1). Metamorphosis was triggered using IBMX in subsequent st...

1. Cantharidin, an inhibitor of protein phosphatase types 1 (PP1) and 2A (PP2A), increased basal tone of bovine isolated coronary artery rings (CARs) with and without endothelium in a time- and concentration-dependent manner with pEC50 values of about 5.1 and 5.2, respectively, for both preparations. 2. Beta-Adrenoceptor stimulation with isoprenaline (Iso; 0.03-100 microM) or inhibition of phos...

Spontaneous contractions of liver fluke muscle were abolished in Ca2+-free saline and by 100 μM nifedipine and reduced by 5 mM cadmium chloride, suggesting that they are dependent on extracellular Ca2+. Caffeine (5 mM) significantly increased contraction amplitude and frequency. Ryanodine (100 μM) failed to block the caffeine response but significantly reduced spontaneous contraction frequency,...

Whole-cell patch-clamp recordings from Vicia faba mesophyll protoplasts reveal that outward K+ current is increased in a dose-dependent fashion by intracellular application of cAMP. The enhancement of the outward current by cAMP is specific and it cannot be mimicked by a series of nucleotides that includes AMP, cGMP, and GMP. The enhancement is evoked by micromolar concentrations of cAMP in the...

The objective of this study was to determine whether the voltage-sensitive release mechanism (VSRM) can be stimulated independently from Ca(2+)-induced Ca(2+) release (CICR) by drugs that elevate intracellular cAMP. Contractions were measured in voltage-clamped guinea pig ventricular myocytes at 37 degrees C. Na(+) current was blocked. We compared effects of agents that elevate cAMP through act...

Cornus officinalis is widely distributed in Korea, and its fruit has been used to make as herbal drug for traditional medicine in Korea, Japan, and China because of its tonic, analgesic, and diuretic properties. However, the effects of C. officinalis methanol extract (COME) on melanogenesis remain poorly understood. We evaluated the melanogenic capability of COME in melan-a cells, which are imm...

Bovine oocytes cultured in control medium or in medium containing dibutyrylcyclic adenosine monophosphate (dbcAMP) or an inhibitor of cyclic nucleotide phosphodiesterase (3-isobutyl-1-methylxanthine, IBMX) undergo germinal vesicle breakdown (GVBD). On the other hand, mouse oocytes remain arrested at the germinal vesicle (GV) stage when dbcAMP or IBMX is present. When 1 bovine GV stage oocyte is...

We used our recently reported stable, transformed human renal carcinoma cell line as a model system to study the role of 3',5'-adenosine monophosphate (cAMP) in erythropoietin secretion. The erythropoietin produced by these cells is both biologically active and immunologically cross-reactive with purified native human hormone in our radioimmunoassay. Erythropoietin release by these renal carcin...

Objective(s): Recently, we showed that some new synthetic compounds structurally related to cilostamide (4-(1,2-dihydro-2-oxoquinolin-6-hydroxy)- N-cyclohexyl-N-methylbutanamide), a selective phosphodiesterase 3 (PDE3) inhibitor, produce inotropic effect comparable to that of IBMX (3-isobutyl-1-methylxanthine), a non-selective PDE inhibitor, but with differential chronotropic effect. In this in...