Toxicokinetic study of rat intestinal brush border membrane enzymes following in vitro exposure to lead and vanadium

1994 ◽  
Vol 52 (6) ◽  
Author(s):  
K. Gupta ◽  
R.K. Upreti ◽  
A.M. Kidwai
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Intestinal Brush Border Membrane ◽  
Membrane Enzymes ◽  
Intestinal Brush Border ◽  
In Vitro Exposure ◽  
Brush Border Membrane Enzymes

Adaptation of rabbit small intestinal brush-border membrane enzymes after extensive bowel resection

1995 ◽  
Vol 30 (7) ◽  
pp. 1000-1003 ◽  
Author(s):  
Fresca Swaniker ◽  
Weihong Guo ◽  
Eric W Fonkalsrud ◽  
Tammy Brown ◽  
Laura Newman ◽  
...  
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Bowel Resection ◽  
Intestinal Brush Border Membrane ◽  
Membrane Enzymes ◽  
Intestinal Brush Border ◽  
Small Intestinal ◽  
Brush Border Membrane Enzymes

Hemileaflet susceptibility to oxidative damage in the intestinal brush-border membrane

1995 ◽  
Vol 268 (2) ◽  
pp. G260-G269
Author(s):  
D. Jourd'heuil ◽  
S. Mehta ◽  
J. B. Meddings
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Peroxyl Radical ◽  
Tissue Injury ◽  
Biological Membranes ◽  
First Order ◽  
Intestinal Brush Border Membrane ◽  
Outer Leaflet ◽  
Intestinal Brush Border

Oxidation of biological membranes is characteristic of many types of tissue injury, including those observed with inflammatory bowel disease. The lipid compositions of the inner and outer leaflets of biological membranes differ significantly, making one leaflet theoretically more susceptible to oxidative stress than the other. In this study, we evaluated the susceptibility of each membrane hemileaflet for peroxyl radical-mediated oxidation. In vitro peroxidation of intestinal brush-border membrane was initiated with the peroxyl radical-generator 2,2'-azobis-(2-amidinopropane)hydrochloric acid (AAPH). Oxidation events were monitored by following the oxidation-sensitive degradation of the lipid-soluble fluorescent probe cis-parinaric acid (PnA). The degradation patterns were clearly distinct in the inner and outer hemileaflet. PnA degradation in the inner hemileaflet was consistent with a slow first-order reaction, whereas degradation in the outer leaflet appeared as two first-order processes delayed in time. The results suggest that the sum of available antioxidants and endogenous substrates for oxidation are consumed more rapidly in the outer membrane hemileaflet, making this leaflet more susceptible to peroxidation compared with the cytofacial leaflet.

Characterization and modulation of rat small intestinal brush-border membrane transbilayer fluidity

1991 ◽  
Vol 260 (4) ◽  
pp. G586-G594
Author(s):  
P. K. Dudeja ◽  
R. K. Wali ◽  
J. M. Harig ◽  
T. A. Brasitus
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Leucine Aminopeptidase ◽  
Aminopeptidase Activity ◽  
Intestinal Brush Border Membrane ◽  
Intestinal Brush Border ◽  
Leucine Transport ◽  
Small Intestinal

In the present experiments, selective quenching by trinitrophenyl groups as well as steady-state fluorescence polarization and differential polarized phase fluorescence techniques, using three different lipid soluble fluorophores, were used to directly examine the fluidity of the exofacial and cytofacial leaflets of rat small intestinal brush-border membranes. These studies revealed that the fluidity of the exofacial hemileaflet was greater than the cytofacial hemileaflet. Differences in the distribution of phosphatidylcholine and phosphatidylethanolamine, as assessed by phospholipase A2 treatment and trinitrophenylation of aminophospholipids, were, at least partially, responsible for the asymmetrical fluidity of the hemileaflets. Moreover, in vitro addition of benzyl alcohol (final concn 25 mM) preferentially fluidized the exofacial leaflet and concomitantly decreased leucine aminopeptidase activity but did not affect the activities of maltase, sucrase, alkaline phosphatase, or gamma-glutamyltranspeptidase. In vivo addition of the membrane-mobility agent 2-(2-methoxyethoxy)ethyl 8-(cis-2-n-octylcyclopropyl)octanate] (A2C) (final concn 7.5 microM) preferentially fluidized the cytofacial leaflet and increased Na(+)-gradient-dependent D-glucose transport but not Na(+)-gradient-dependent L-leucine transport.

scholarly journals The effects of dietary ligands on zinc uptake at the porcine intestinal brush-border membrane

1990 ◽  
Vol 64 (3) ◽  
pp. 733-741 ◽  
Author(s):  
A. J. Turnbull ◽  
P. Blakeborough ◽  
R. P. H. Thompson
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Intestinal Brush Border Membrane ◽  
Intestinal Brush Border ◽  
Zn Uptake ◽  
Zn Concentration ◽  
Vitro Model

Intestinal brush-border-membrane vesicles were prepared from the porcine small bowel by magnesium precipitation and differential centrifugation, and were functionally intact. The influence of dietary ligands on 65Zn uptake was determined using a 65Zn concentration of 5 μm, an incubation time of 1 min and a reaction temperature of 27°, with a rapid filtration technique. At this low Zn concentration the addition of an excess of folate, histidine or glucose had no effect on Zn uptake. Addition of picolinate, citrate and phytate to the incubation medium significantly reduced Zn uptake at all concentrations of ligand examined. Any inhibitory effects of folic acid in vivo may thuss be due to a mucosal rather than lumen interaction. Those ligands inhibiting absorption may have done so through the formation of Zn-ligand complexes, which are either insoluble, or which reduce the binding of Zn to its mucosal receptor. This in vitro model of Zn absorption is useful for comparing the effects of potential Zn-binding ligands in the diet.

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