γ-Radiation induces apoptosis via sarcoplasmatic reticulum in guinea pig ileum smooth muscle cells
Data de publicação2008-08-20
Direito de acesso
MetadadosExibir registro completo
We investigated the effects of γ-radiation on cells isolated from the longitudinal smooth muscle layer of the guinea pig ileum, a relatively radioresistant tissue. Single doses (up to 50 Gy) reduced the amount of sarcoplasmatic reticulum and condensed the myofibrils, as shown by electron microscopy 3 days post-irradiation. After that, contractility of smooth muscle strips was reduced. Ca2+ handling was altered after irradiation, as shown in fura-2 loaded cells, with elevated basal intracellular Ca2+, reduced amount of intrareticular Ca2+, and reduced capacitive Ca2+ entry. Radiation also induced apoptosis, judged from flow cytometry of cells loaded with proprium iodide. Electron microscopy showed that radiation caused condensation of chromatin in dense masses around the nuclear envelope, the presence of apoptotic bodies, fragmentation of the nucleus, detachment of cells from their neighbors, and reductions in cell volume. Radiation also caused activation of caspase 12. Apoptosis was reduced by the administration of the caspase inhibitor Z-Val-Ala-Asp-fluoromethyl-ketone methyl ester (Z-VAD-FMK) during the 3 day period after irradiation, and by the chelator of intracellular Ca2+, 1,2-bis(o-aminophenoxy)-ethane-N,N,N′,N′-tetraacetic acid (BAPTA), from 1 h before until 2 h after irradiation. BAPTA also reduced the effects of radiation on contractility, basal intracellular Ca2+, amount of intrareticular Ca2+, capacitative Ca2+ entry, and apoptosis. In conclusion, the effects of gamma radiation on contractility, Ca2+ handling, and apoptosis appear due to a toxic action of intracellular Ca2+. Ca2+-induced damage to the sarcoplasmatic reticulum seems a key event in impaired Ca2+ handling and apoptosis induced by γ-radiation. © 2008 Elsevier B.V. All rights reserved.
Como citar este documento
Este item aparece nas seguintes coleções
Exibindo os itens relacionados pelo título, autor e palavra-chave.
Dias da Silva, S. R. ; Gonçalves, Mauro (Electromyography and Clinical Neurophysiology, 2006) [Artigo]The objective of this study was to analyze the electromyographic (EMG) signal behavior of rectus femoris (RF), vastus medialis (VM), vastus lateralis (VL) and biceps femoris (caput longum) (BFCL) from nine women during ...
Mouse extensor digitorum longus and soleus show distinctive ultrastructural changes induced by veratrine Da Cruz Höfling, M. A.; Dal Pai Silva, M. ; Silva Freitas, E. M. (Journal of Submicroscopic Cytology and Pathology, 2002) [Artigo]We investigated whether veratrine (5 μl, 10 ng/kg) injected into the mouse extensor digitorum longus (EDL) (fast-twitch) and soleus (SOL) (slow-twitch) muscles provokes distinctive ultrastructural disturbances 15, 30 and ...
Histoenzymological and ultrastructural changes in lateral muscle fibers of Oreochromis niloticus (Teleostei: Cichlidae) after local injection of veratrine Silva Freitas, Erika Maria; Dal Pai Silva, Maeli ; Da Cruz-Höfling, Maria Alice (Histochemistry and Cell Biology, 2001) [Artigo]The effects of veratrine have been investigated in mammalian, amphibian, and crustacean muscle, but not in fish. In this work, the action of veratrine was studied in the lateral muscle of the freshwater teleost Oreochromis ...