12/5/2023 0 Comments Dibutyryl cyclic amp![]() Insulin increased tissue glycogen concentrations in tissue from fetuses of seven or more weeks. These results suggest that the regulation of glycogen levels in human fetal liver by cyclic AMP, glucagon, and insulin may entail alterations in the activity of glycogen synthase activity without necessitating alterations in phosphorylase activity.Ĭyclic AMP or glucagon was capable of depleting tissue glycogen stores in tissue from fetuses of six weeks’ gestation. In neither circumstance was the proportion of active phosphorylase altered. Incubation with dibutyryl cyclic AMP resulted in a decrease of glycogen synthase I-form activity, while insulin tended to increase this enzyme activity. The cells were then exposed to 50 mM H 2 O 2 for 1 h, and their viability measured (CFUs). albicans RM1000 cells were grown on lactate (YPL) and then incubated for 1 h with 1 glucose, dbcAMP, or a combination of both. Insultin had no consistent effect on cyclic AMP output in either the presence or the absence of glucagon or theophylline. (D) The cAMP analogue, dibutyryl-cyclic AMP (dbcAMP), inhibits glucose-enhanced oxidative stress resistance. Glucagon stimulated cyclic AMP output from explants, and this effect was further augmented by theophylline. Insulin antagonized the glycogenolytic effect of low doses of glucagon or theophylline but was without significant effect in the presence of high glucagon concentrations. The response to dibutyryl cyclic AMP was apparent by one hour and maximal by three to six hours, whereas the response to insulin required about six hours to be detected, and it continued for at least eighteen hours. After the treatment with dibutyryl-cyclic AMP, the cells ceased proliferation and extended neurite-like processes that were immunostained with the antibody against tubulin betaIII, a marker of immature neurons. The effect of maximal doses of dibutyryl cyclic AMP and glucagon were the same, and the combination of agents produced no further effect. FBBC-1 cells are stable after passaging to >100 population doublings after single cell cloning, with a generation time of 24h. Incubation with glucagon, cyclic AMP (adenosine 3ʹ,5ʹ-monophosphate) or its dibutyryl derivative markedly reduced tissue glycogen concentrations while insulin brought about a small increase. Total phosphorylase activity increases slightly during this period, with the proportion in the active form amounting to about one half of the total throughout.Īfter an initial rapid decline, the glycogen concentration in explants of human fetal liver remained constant for twenty to forty hours at about 20 per cent of the in vivo level. A parallel increase in total glycogen synthase activity is found, although the I-form activity remains low and constant throughout the first two thirds of gestation. Glycogen accumulates in human fetal liver beginning at the eighth week of gestation.
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