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1.
Asian Pacific Journal of Tropical Medicine ; (12): 407-409, 2013.
Article Dans Anglais | WPRIM | ID: wpr-820033

Résumé

OBJECTIVE@#To discuss effect of ionizing radiation on transcription of colorectal cancer multidrug resistance (MDR) 1 gene of HCT-8 cells.@*METHODS@#Total RNA was extracted by guanidine thiocyanate one-step method. Northern blot was applied to detect transcription level of MDR1 gene. The expression of P-gp protein was detected by flow cytometry.@*RESULTS@#The expression of MDR1 of normal colorectal cancer HCT-8 cells was low. It was increased by 8.35 times under stimulus with 2 Gy. When treated with low doses in advance, high expressed MDR was decreased significantly under 0.05, 0.1 Gy, which was 69.00%, 62.89% in 2 Gy group and 5.77 times, 5.25 times in sham irradiation group. No obvious difference was detected between (0.2+2) Gy group and 2 Gy group. Compared with sham irradiation group, the percentage of P-gp positive cells after radiation of a high 2 Gy dose was increased significantly (P<0.01). When treated with high radiation dose following low radiation dose (0.05 Gy, 0.1 Gy) in advance, the percentage of P-gp positive cells were also increased significantly. The percentage of P-gp positive cells were increased obviously in 0.2 Gy and 2 Gy groups. Compared with simple high radiation 2 Gy group, the percentage of P-gp positive cells was decreased significantly (P<0.05).@*CONCLUSIONS@#Low radiation dose can reverse multidrug resistance of colorectal cancer cells caused by high radiation dose.


Sujets)
Humains , Sous-famille B de transporteurs à cassette liant l'ATP , Glycoprotéine P , Génétique , Lignée cellulaire tumorale , Tumeurs colorectales , Génétique , Métabolisme , ARN messager , Génétique , Métabolisme , ARN tumoral , Génétique , Métabolisme , Rayonnement ionisant , Transcription génétique , Effets des rayonnements
2.
Acta Pharmaceutica Sinica ; (12): 491-495, 2005.
Article Dans Chinois | WPRIM | ID: wpr-353487

Résumé

<p><b>AIM</b>To investigate the role and mechanism of endothelium-derived hyperpolarizing factor (EDHF) in shear stress induced vasorelaxation of rat mesenteric artery.</p><p><b>METHODS</b>The changes in vessel diameter in response to variable flow (0-300 microL.min(-1)) were continuously examined. The contribution of prostacyclin (PGI2), NO and EDHF to shear stress induced relaxation were analyzed by inhibitory effects of indomethacin, N(G)-nitro-L-arginine (L-NA) and KCl. The nature and hyperpolarizing mechanism of EDHF were examined by the inhibitory effects of inhibitors of cytochrome P450 pathway and of various K+ channels.</p><p><b>RESULTS</b>The shear stress-induced relaxation were endothelium dependent and the contribution of NO was more prominent in large mesenteric arteries (400-500 microm) than that in resistance arteries (150-250 microm), whereas that of EDHF was noted in both-sized blood vessels. Tetrabutylammonium (a nonselective inhibitor of K channels) almost abolished, whereas the combination of charybdotoxin (an inhibitor of both large and intermediate-conductance Ca2+-activated K channels) and apamin (an inhibitor of small-conductance Ca2+-activated K channels) significantly inhibited the EDHF-mediated component of the shear stress-induced relaxations.</p><p><b>CONCLUSION</b>EDHF plays an important role in shear stress-induced endothelium-dependent relaxations, and K channels especially calcium-activated K channels appear to be involved.</p>


Sujets)
Animaux , Mâle , Rats , Apamine , Pharmacologie , Facteurs biologiques , Physiologie , Charybdotoxine , Pharmacologie , Inhibiteurs des enzymes du cytochrome P-450 , Endothélium vasculaire , Physiologie , Techniques in vitro , Canaux potassiques calcium-dépendants de grande conductance , Artères mésentériques , Physiologie , Monoxyde d'azote , Physiologie , Inhibiteurs des canaux potassiques , Pharmacologie , Proadifène , Pharmacologie , Composés d'ammonium quaternaire , Pharmacologie , Rat Wistar , Canaux potassiques calcium-dépendants de petite conductance , Vasodilatation
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