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The action of prostaglandins E1 and F2 alpha on adenylate cyclase and cAMP phosphodiesterase was assayed in cell membrane fractions of amnion obtained before and after labor from term physiological pregnancies. Both prostaglandins stimulate the activity of adenylate cyclase in a dose-dependent manner. After spontaneous delivery both prostaglandins stimulate(More)
The effects of different neuroactive agents on cyclic AMP level of selected ganglia of Planorbis corneus were studied. Serotonin, dopamine and prostaglandin E(2) were capable of increasing significantly cyclic AMP synthesis in all the preparations. When such substances were tested in pairs, supra-additive effects were always observed. In high Ca(2+)-high(More)
The effect of RMI 12330A, an inhibitor of basal as well as serotonin-stimulated adenylate cyclase in the segmental ganglia of the leech Hirudo medicinalis, has been tested on cyclic AMP-phosphodiesterase activity in the same tissue. The drug dose-dependently inhibits high and low affinity enzyme, an effect first evident at an RMI 12330A concentration of 0.5(More)
Adenylate cyclase activity has been measured in segmental ganglia of the leech Hirudo m. Basal enzymatic activity was stimulated in a dose dependent fashion by serotonin. GTP is required in order to evoke maximal stimulation. The effect was blocked by methysergide, an antagonist of serotonin at receptor level. The stimulation of the enzyme was prevented by(More)
The effects of Mn2+ and calmodulin were studied on the basal and agonist-modulated adenylate cyclase activity of the guinea pig superior cervical ganglion. The divalent cation strongly stimulates the basal and agonist-modulated enzyme in a concentration-dependent manner. Moreover, in the presence of Mn2+ the inhibitory effects of “high” GTP concentrations(More)
Basal activity and response to insulin of adenylate cyclase and cyclic AMP-phosphodiesterase were measured in the fetal membranes before and after labor. Basal activity of adenylate cyclase showed only slight variations after delivery when compared to that observed before labor. Enzyme activity was significantly although weakly decreased by insulin both in(More)
1. The effects of different neurotransmitters on cAMP levels in segmental ganglia ofHirudo were studied. Serotonin and dopamine caused a significant increase in cAMP levels. Norepinephrine, octopamine, glutamate, and carbachol were ineffective. 2. The stimulation of cAMP levels by dopamine was blocked by increasing the concentration of Mg2+ ions in the(More)
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