Search Results - (Author, Cooperation:L. Conforti)

2012-06-09

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Animals ; Animals, Genetically Modified ; Apoptosis ; Armadillo Domain Proteins/analysis/*genetics/*physiology ; Axons/*physiology/ultrastructure ; Axotomy ; Cell Survival ; Cells, Cultured ; Cytoskeletal Proteins/analysis/*genetics/*physiology ; Denervation ; Drosophila/embryology/genetics/physiology ; Drosophila Proteins/analysis/*genetics/*physiology ; Mice ; Mutation ; Neurons/*physiology ; Sciatic Nerve/injuries/physiology ; Signal Transduction ; Superior Cervical Ganglion/cytology ; Tissue Culture Techniques ; *Wallerian Degeneration

0305-0491

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Chemistry and Pharmacology

Electronic Resource

1420-908X

Key words: Semicarbazide-sensitive amine oxidases — Histaminases — Rat white adipocyte pharmacology

Springer Online Journal Archives 1860-2000

Medicine

Abstract. Objective and Design: Investigate the reaction conditions which allow the measurement of high affinity histamine oxidation.¶Material: Isolated rat white adipocytes.¶Methods: The histaminase activity of rat white adipocytes and its inhibition by B24 and MDL 72274 was measured fluorimetrically or radiochemically in different experimental conditions.¶Results: Histamine oxidation by rat white adipocytes is enhanced by elevated pH and by the presence of bicarbonate ions. Under these conditions the oxidative deamination of histamine by white adipocytes, becomes comparable to that of other histaminases, suggesting that this amine oxidase activity may play a role in the catabolism of histamine in vivo. The specific semicarbazide-sensitive amine oxidase (SSAO) inhibitors MDL 72274 and B24 inhibit the oxidation of both histamine and benzylamine by the adipocyte preparation.¶Conclusions: Although there are kinetic differences between the behaviour of these two amine substrates, these results would be consistent with a SSAO being responsible for both activities.

Electronic Resource

1432-2013

Calcium current Dopamine receptor G protein Hypoxia Pertussin toxin Quinpirole

Springer Online Journal Archives 1860-2000

Medicine

Abstract. We have previously shown that pheochromocytoma (PC12) cells rapidly depolarize and undergo Ca2+ influx through voltage-dependent Ca2+ channels in response to moderate hypoxia and that intracellular free Ca2+ is modulated by activation of dopamine D2 receptors in this cell type. The present study shows that D2 (quinpirole-mediated) inhibition of a voltage-dependent Ca2+ current (I Ca) in PC12 cells is dramatically attenuated after chronic exposure to moderate hypoxia (24 h at 10% O2). Pretreatment of cells with pertussis toxin abolished D2-mediated inhibition of I Ca. The D2-induced inhibition of I Ca did not depend on protein kinase A (PKA), as it persisted both in the presence of a specific PKA inhibitor (PKI) and in PKA-deficient PC12 cells. Prolonged exposure to hypoxia (24 h) significantly reduced the level of Gi/oα immunoreactivity, but did not alter Gβ levels. Furthermore, dialysis of recombinant Goα protein through the patch pipette restored the inhibitory effect of quinpirole in cells chronically exposed to hypoxia. We conclude that the attenuation of the D2-mediated inhibition of I Ca by chronic hypoxia is caused by impaired receptor–G protein coupling, due to reduced levels of Goα protein. This attenuated feedback modulation of I Ca by dopamine may allow for a more sustained Ca2+ influx and enhanced cellular excitation during prolonged hypoxia.

Electronic Resource