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1.
Braz. j. med. biol. res ; 45(1): 20-24, Jan. 2012. ilus, tab
Article Dans Anglais | LILACS | ID: lil-610552

Résumé

The aim of this study was to determine the correlation between total nitrite/nitrate concentrations (NOx) and the kinetic parameters of monoamine oxidase enzymes (MAO-A and MAO-B) and semicarbazide-sensitive amine oxidase (SSAO) in human mesenteric arteries. Arteries were from non-diabetic and type 2 diabetic patients with sigmoid or rectum carcinoma for whom surgery was the first option and who were not exposed to neo-adjuvant therapy. Segments of human inferior mesenteric arteries from non-diabetic (61.1 ± 8.9 years old, 7 males and 5 females, N = 12) and type 2 diabetic patients (65.8 ± 6.2 years old, 8 males and 4 females, N = 12) were used to determine NOx concentrations and the kinetic parameters of MAO-A, MAO-B and SSAO by the Griess reaction and by radiochemical assay, respectively. The NOx concentrations in arteries from diabetic patients did not differ significantly from those of the non-diabetic group (10.28 ± 4.61 vs 10.71 ± 4.32 nmol/mg protein, respectively). In the non-diabetic group, there was a positive correlation between NOx concentrations and MAO-B parameters: Km (r = 0.612, P = 0.034) and Vmax (r = 0.593, P = 0.042), and a negative correlation with the SSAO parameters: Km (r = -0.625, P = 0.029) and Vmax (r = -0.754, P = 0.005). However, in the diabetic group no correlation was found between NOx concentrations and the three kinetic parameters of the enzymes. These results suggest an important function of sympathetic nerves and vascular NOx concentrations in arteries of non-diabetic patients. Thus, these results confirm the importance of a balance between oxidants and antioxidants in the maintenance of vascular homeostasis to prevent oxidative stress.


Sujets)
Sujet âgé , Femelle , Humains , Adulte d'âge moyen , Amine oxidase (copper-containing)/métabolisme , /métabolisme , Artères mésentériques/composition chimique , Monoamine oxidase/métabolisme , Nitrates/analyse , Nitrites/analyse , Études cas-témoins , /enzymologie , Artères mésentériques/enzymologie , Tumeurs du rectum/enzymologie , Tumeurs du sigmoïde/enzymologie
2.
Braz. j. med. biol. res ; 42(9): 844-853, Sept. 2009. ilus, tab, graf
Article Dans Anglais | LILACS | ID: lil-524316

Résumé

Multiple cell membrane alterations have been reported to be the cause of various forms of hypertension. The present study focuses on the lipid portion of the membranes, characterizing the microviscosity of membranes reconstituted with lipids extracted from the aorta and mesenteric arteries of spontaneously hypertensive (SHR) and normotensive control rat strains (WKY and NWR). Membrane-incorporated phospholipid spin labels were used to monitor the bilayer structure at different depths. The packing of lipids extracted from both aorta and mesenteric arteries of normotensive and hypertensive rats was similar. Lipid extract analysis showed similar phospholipid composition for all membranes. However, cholesterol content was lower in SHR arteries than in normotensive animal arteries. These findings contrast with the fact that the SHR aorta is hyporeactive while the SHR mesenteric artery is hyperreactive to vasopressor agents when compared to the vessels of normotensive animal strains. Hence, factors other than microviscosity of bulk lipids contribute to the vascular smooth muscle reactivity and hypertension of SHR. The excess cholesterol in the arteries of normotensive animal strains apparently is not dissolved in bulk lipids and is not directly related to vascular reactivity since it is present in both the aorta and mesenteric arteries. The lower cholesterol concentrations in SHR arteries may in fact result from metabolic differences due to the hypertensive state or to genes that co-segregate with those that determine hypertension during the process of strain selection.


Sujets)
Animaux , Mâle , Rats , Aorte/composition chimique , Membrane cellulaire/composition chimique , Cholestérol/analyse , Hypertension artérielle/métabolisme , Artères mésentériques/composition chimique , Phospholipides/analyse , Cholestérol/composition chimique , Spectroscopie de résonance de spin électronique , Chromatographie gazeuse-spectrométrie de masse , Hypertension artérielle/étiologie , Muscles lisses vasculaires/composition chimique , Muscles lisses vasculaires/cytologie , Phospholipides/composition chimique , Rats de lignée SHR , Rats de lignée WKY
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