Direct intraperitoneal resuscitation with lidocaine, methylene blue and pentoxiphylline combination does not decreases inflammation after intestinal ischemia-reperfusion injury in rats

ABSTRACT PURPOSE: To evaluate the effects of an intraperitoneal solution of methylene blue (MB), lidocaine and pentoxyphylline (PTX) on intestinal ischemic and reperfusion injury METHODS: Superior mesenteric artery was isolated and clamped in 36 adult male Sprague Dawley rats. After 60 minutes, clamp was removed and a group received intraperitoneally UNITO solution (PTX 25mg/kg + lidocaine 5mg/kg + MB 2mg/kg), while the other group was treated with warm 0.9% NaCl solution. Rats were euthanized 45 min after drug administration. Lung and bowel were collected for histological evaluation (using Park's score) and determination of myeloperoxidase (MPO) and malondialdehyde (MDA) levels. RESULTS: Control samples showed lymphoplasmocytic infiltrate and crypt necrosis of villi. MPO and MDA measurements shown no differences between treated and control groups. CONCLUSION: The combination of lidocaine, methylene blue and pentoxyphylline administered intraperitoneally at the studied dose, did not decreased histological lesion scores and biochemical markers levels in intestinal ischemia/reperfusion injury.

Are there gender differences in left ventricular remodeling after myocardial infarction in rats? / Há diferenças entre os gêneros no remodelamento ventricular esquerdo após infarto do miocárdio em ratos?

Objective: An unclear issue is whether gender may influence at cardiac remodeling after myocardial infarction (MI). We evaluated left ventricle remodeling in female and male rats post-MI. Methods: Rats were submitted to anterior descending coronary occlusion. Echocardiographic evaluations were performed on the first and sixth week post-occlusion to determine myocardial infarction size and left ventricle systolic function (FAC, fractional area change). Pulsed Doppler was applied to analyze left ventricle diastolic function using the following parameters: E wave, A wave, E/A ratio. Two-way ANOVA was applied for comparisons, complemented by the Bonferroni test. A P≤=0.05 was considered significant. Results: There were no significant differences between genders for morphometric parameters on first (MI [Female (FE): 44.0±5.0 vs. Male (MA): 42.0±3.0%]; diastolic [FE: 0.04±0.003 vs. MA: 0.037±0.005, mm/g] and systolic [FE: 0.03±0.0004 vs. MA: 0.028±0.005, mm/g] diameters of left ventricle) and sixth (MI [FE: 44.0±5.0 vs. MA: 42.0±3.0, %]; diastolic [FE: 0.043±0.01 vs. MA: 0.034±0.005, mm/g] and systolic [FE: 0.035±0.01 vs. MA: 0.027±0.005, mm/g] of LV) week. Similar findings were reported for left ventricle functional parameters on first (FAC [FE: 34.0±6.0 vs. MA: 32.0±4.0, %]; wave E [FE: 70.0±18.0 vs. MA: 73.0±14.0, cm/s]; wave A [FE: 20.0±12.0 vs. MA: 28.0±13.0, cm/s]; E/A [FE: 4.9±3.4 vs. MA: 3.3±1.8]) and sixth (FAC [FE: 29.0±7.0 vs. MA: 31.0±7.0, %]; wave E [FE: 85.0±18.0 vs. MA: 87.0±20.0, cm/s]; wave A [FE: 20.0±11.0 vs. MA: 28.0±17.0, cm/s]; E/A [FE: 6.2±4.0 vs. MA: 4.6±3.4]) week. Conclusion: Gender does not influence left ventricle remodeling post-MI in rats. .

Objetivo: A influência do gênero no remodelamento cardíaco após o infarto do miocárdio é uma questão em intenso debate. Nós avaliamos o remodelamento ventricular esquerdo em ratos infartados de ambos os gêneros. Métodos: O infarto do miocárdio foi induzido por oclusão da artéria coronária descendente anterior (fêmeas [FM]; machos [MC]). A ecocardiografia foi realizada na primeira e sexta semana pós-oclusão para determinar o tamanho do infarto do miocárdio e a função sistólica do ventricular esquerdo (mudança na área fracional [FAC]). A função diastólica derivou dos seguintes parâmetros: onda E; onda A; razão E/A. ANOVA duas vias com pós-teste de Bonferroni foi aplicado nas comparações (P≤=0,05). Resultados: Todas variáveis morfométricas foram similares (P>0,05) entre os gêneros com uma (infarto do miocárdio [FM: 44,0±5,0 vs. MC: 42,0±3,0, %]; diâmetro diastólico [FM: 0,04±0,003 vs. MC: 0,037±0,005, mm/g] e sistólico [FM: 0,03±0,0004 vs. MC: 0,028±0,005, mm/g] do VE) e seis (IM [FM: 44,0±5,0 vs. MC: 42,0±3,0, %]; diâmetro diastólico [FM: 0,043±0,01 vs. MC: 0,034±0,005, mm/g] e sistólico [FM: 0,035±0,01 vs. MC: 0,027±0,005, mm/g] do ventricular esquerdo) semanas. Achado similar ocorreu para os dados funcionais com uma (FAC [FM: 34,0±6,0 vs. MC: 32,0±4,0, %]; onda E [FM: 70,0±18,0 vs. MC: 73,0±14,0, cm/s]; onda A [FM: 20,0±12,0 vs. MC: 28,0±13,0, cm/s]; E/A [FM: 4,9±3,4 vs. MC: 3,3±1,8]) e seis (FAC [FM: 29,0±7,0 vs. MC: 31,0±7,0, %]; onda E [FM: 85,0±18,0 vs. MC: 87,0±20,0, cm/s]; onda A [FM: 20,0±11,0 vs. MC: 28,0±17,0 cm/s]; E/A [FM: 6,2±4,0 vs. MC: 4,6±3,4]) semanas. Conclusão: O gênero não é determinante para o remodelamento ventricular esquerdo pós-infarto do miocárdio em ratos. .

Are levels of digestive enzyme activity related to the natural diet in passerine birds?

Digestive capabilities, such as the rates nutrient hydrolysis and absorption, may affect energy intake and ultimately feeding behavior. In birds, a high diversity in gut biochemical capabilities seems to support the existence of a correlation between the morphology and physiology of the intestinal tract and chemical features of the natural diet. However, studies correlating the activity of digestive enzymes and the feeding habits at an evolutionary scale are scarce. We investigated the effect of dietary habits on the digestive physiological characteristics of eight species of passerine birds from Central Chile. The Order Passeriformes is a speciose group with a broad dietary spectrum that includes omnivorous, granivorous and insectivorous species. We measured the activity of three enzymes: maltase, sucrase and aminopeptidase-N. Using an autocorrelation analysis to remove the phylogenetic effect, we found that dietary habits had no effect on enzymatic activity. However, we found that granivorous and omnivorous species had higher levels of disaccharidase activities and insectivores had the lowest. The major difference in enzymatic activity found at the inter-specific level, compared to the reported lower magnitude of enzyme modulation owing to dietary acclimation, suggests that these differences to some extent have a genetic basis. However, the lack of a clear association between diet categories and gut physiology suggested us that dietary categorizations do not always reflect the chemical composition of the ingested food.

Effect of gallic acid on alkaline phosphatase and peptidase activities in rat intestine.

Gallic acid is a normal constituent of many edible foods, thus directly interacts with epithelial tissue in intestine. In the present study, the effect of gallic acid on intestinal alkaline phosphatase (IAP) and peptidase activities in rat intestine was evaluated. Gallic acid (0.27-0.5 mM) inhibited activities of leucine aminopeptidase (LAP) and -glutamyl transpeptidase (-GTP) by over 90%, compared to controls in rat intestine. In contrast, 0.1-0.6 mM gallic acid either had no effect or stimulated the activity of IAP in rat intestine. The observed inhibition of peptidases by gallic acid was reversible in nature. Kinetic analysis revealed no change in Vmax of LAP (0.42-0.44 units/mg protein) and -GTP (0.22-0.24 units/mg protein), while the values of apparent Km were increased 6-7 fold, exhibiting competitive-type of enzyme inhibition by gallic acid. The values of Ki for LAP and -GTP were 0.037 mM and 0.017 mM, respectively. These observations indicate that gallic acid is a potent inhibitor of brush border peptidases, and thus may interfere in the digestion and absorption of proteins in the intestine.

Perspectives of digestive pest control with proteinase inhibitors that mainly affect the trypsin-like activity of Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae)

The present study describes the main characteristics of the proteolytic activities of the velvetbean caterpillar, Anticarsia gemmatalis Hübner, and their sensitivity to proteinase inhibitors and activators. Midguts of last instar larvae reared on an artificial diet were homogenized in 0.15 M NaCl and centrifuged at 14,000 g for 10 min at 4°C and the supernatants were used in enzymatic assays at 30°C, pH 10.0. Basal total proteolytic activity (azocasein hydrolysis) was 1.14 ± 0.15 absorbance variation min-1 mg protein-1, at 420 nm; basal trypsin-like activity (N-benzoyl-L-arginine-p-nitroanilide, BApNA, hydrolysis) was 0.217 ± 0.02 mmol p-nitroaniline min-1 mg protein-1. The maximum proteolytic activities were observed at pH 10.5 using azocasein and at pH 10.0 using BApNA, this pH being identical to the midgut pH of 10.0. The maximum trypsin-like activity occurred at 50°C, a temperature that reduces enzyme stability to 80 and 60 percent of the original, when pre-incubated for 5 and 30 min, respectively. Phenylmethylsulfonyl fluoride inhibited the proteolytic activities with an IC50 of 0.39 mM for azocasein hydrolysis and of 1.35 mM for BApNA hydrolysis. Benzamidine inhibited the hydrolysis with an IC50 of 0.69 and 0.076 mM for azocasein and BApNA, respectively. The absence of cysteine-proteinases is indicated by the fact that 2-mercaptoethanol and L-cysteine did not increase the rate of azocasein hydrolysis. These results demonstrate the presence of serine-proteinases and the predominance of trypsin-like activity in the midgut of Lepidoptera insects, now also detected in A. gemmatalis, and suggest this enzyme as a major target for pest control based on disruption of protein metabolism using proteinase inhibitors.

Common Whelk (Buccinum undatum)Allergy:Identification of IgE-binding Components and Effects of Heating and Digestive Enzymes

In Korea, common whelk (Buccinum undatum) is a popular edible shellfish. The aim of this study was to observe the sensitization rate to common whelk and to characterize its allergens. We carried out skin prick test (SPT) in 1,700 patients with various allergic diseases. Specific IgE were detected by ELISA in the patient sera and ELISA inhibition tests were conducted. IgE-binding components were identified by means of SDS-PAGE and IgE-immunoblotting. The effects of diges-tive enzymes were evaluated in both raw and thermally treated extracts. SPT to common whelk was positive (> or =2+) in 83 (4.9%) patients studied. Twenty-four (38.7%) out of 62 SPT positive patients had high serum specific IgE to common whelk. ELISA inhibition test showed significant inhibitions by abalone as well as by common whelk. IgE-immunoblotting demonstrated three IgE-binding components (40, 71, 82 kDa), which were digested by simulated intestinal fluid and moderately digested by simulated gastric fluid, and the digestibility of allergens remained unchanged after thermal treatment. In conclusion, IgE-sensitization rate to com-mon whelk was 4.9% in allergy patients. IgE-immunoblotting demonstrated three IgE-binding components, which were degraded by digestive enzymes. Further studies are needed to evaluate the clinical significance of the sensitized patients to common whelk.

Enhanced esterase activity in salivary gland and midgut of Aedes aegypti mosquito infected with dengue-2 virus.

Mosquitoes were infected by intrathoracic inoculation. About 95% head squashes were positive for dengue virus antigen on the 15th post infection day (PID). Esterase activity was determined in the homogenates prepared from the salivary glands and midguts on different PIDs of dengue virus inoculated and control mosquitoes showed that it was consistently higher in the virus-infected batches.

Trypsin and aminopeptidase activities in blood-fed females Anopheles dirus (Diptera: Culicidae) of differing susceptibility to Plasmodium yoelii nigeriensis.

Midgut proteolytic enzymes contribute to the success or failure of Plasmodium infection of the mosquito. The present study investigated trypsin and aminopeptidase activities in the midgut of two strains of Anopheles dirus selected for susceptibility and refractoriness to Plasmodium yoelii nigeriensis. At intervals of 6 hours following a bloodmeal, the midguts of fully engorged female mosquitos were dissected, homogenized, and assayed for enzyme activity. No differences trypsin activity (nmole/min) were observed between the two strains throughout the course of blood digestion. By contrast, the aminopeptidase activity measured at 0 to 18 hours post-feeding was the same for the two strains, but at 24, 30 and 36 hours significantly less activity was observed in the refractory females. The results suggest neither trypsin nor aminopeptidase plays a role in the limitation of parasite development.

Mecanismos de açäo e controle da digestäo de proteínas e peptídios em humanos / Human protein digestive activity and control

Este trabalho objetiva rever os principais mecanismos controladores da digestão de proteínas e peptídeos de interesse especial para humanos. O processo de digestão e aproveitamento protéico tem início no estômago com ações não tão indispensáveis como as do lúmen duodeno/jejunal. Entretanto, mesmo esses processos intestinais estão parcialmente sob controle da secreção gástrica. As atividades proteolíticas das enzimas são relacionadas à estrutura protéica e seus aminoácidos constituintes. Estruturas terciárias e quaternárias necessitam da desnaturação com ácido clorídrico antes de sofrerem hidrólise enzimática. A seguir, há ação das exopeptidases guiadas pelos terminais NH2 (amino peptidases) e COOH (carboxipeptidases) da molécula, enquanto as endopeptidases são orientadas pelos aminoácidos constituintes da molécula peptídica. Deste modo, tanto os polipeptídios e proteínas dietéticas como as secretadas no lúmen sofrem proteólise limitada ou completa resultando di-octapeptídios (60 por cento) ou aminoácidos livres (40 por cento). As peptidases da borda em escova continuam a degradação até di-tripeptídios ou aminoácidos livres (neutros). Alguns peptídios escapam a essa ação e são captados pelo enterócito, cujas peptidases citosólicas completam a hidrólise. Desta forma, os produtos da digestão, circulantes na veia porta, são constituídos de aminoácidos livres e alguns di-tripeptídios. Os processos mecânicos e químicos da digestão sofrem controle neural (vagal), neuroendócrino (acetilcolina), endócrino (gastrina, secretina, colecistocinina) ou parácrino (histamina). A fase gástrica (secreções de ácido clorídrico e pepsinogênio) é ativada pela gastrina, histamina e acetilcolina em resposta tanto aos aminoácidos dietéticos (triptofano e fenilalanina) como a distensão mecânica do estômago. A secreção pancreática é estimulada pelas fases cefálica e gástrica e influencia a fase intestinal da digestão. As células intestinais tipos S e I liberam secretina e colecistocinina, respectivamente, em resposta ao quimo ácido (célula S) ou aminoácidos e peptídios no lúmen (célula I). A secretina estimula a lilberação de água, bicarbonato e enteropeptidases enquanto a colecistocinina libera as enzimas pancreáticas.

Expression of brush border enzymes in ethanol fed rat intestine.

The effect of feeding ethanol daily for 40 days was studied on various brush border enzymes in rat intestine. Brush border alkaline phosphatase (AP), lactase, gamma-glutamyltranspeptidase (gamma-GTP), p-nitrophenyl (PNP)-beta-D-galactosidase (P < 0.01) and sucrase (P < 0.001) were significantly enhanced while leucine aminopeptidase and PNP-beta-D-glucosidase activities were unaltered in ethanol fed rats compared to the controls. Kinetic studies revealed that an increase in Vmax together with a decrease in affinity in case of gamma-GTP and an increase in Vmax for AP and sucrase were responsible for the observed stimulation of enzyme activities in ethanol administered rats. Significant changes in enzyme activities were observed in different populations of enterocytes along the crypt-villus unit in the ethanol fed animals. These observations suggest that ethanol feeding modifies the brush border enzymes in rat intestine but the underlying mechanisms seem to be distinct in differentiating enterocytes.

Kinetic studies on the membrane form of intestinal alkaline phosphatase

We have purified different membrane and soluble forms of alkaline phosphatase from human placenta and bovine intestine. The enzymes will be used as markers in immunoconjugates and/or as model for membrane enzyme studies. The membrane formof alkaline phosphatase extracted from bovine intestine was purified on Q-Sepharose and on L-histidyldiazobenzylphosphonic acid-agarose columns to remove phosphodiesterase activity. The purified enzyme had a molecular mass of 61 kDa, Km of 1208 µM, and Vmax 240 µmol pNP/min when assayed in 1 M diethanolamine, 0.5 mM MgCl2 buffer, pH 9.8, containing 10 to 2250 µM of pNPP at 37§C. In the present investigation we studied the effect of salts and inositol derivatives on this enzyme activity, which was found to depend on 0.5 mM Mg2+, and to be fully inhibited by 1.2 mM Hg2+. Vanadate (0.5 mM) and Zn2+ (0.5 mM) reduced the Km value by 43 percent and 84 percent, respectively. Inositol (2 mM) and inositol-2-monophosphate (2 mM) reduced the activity by 23 percent and 17 percent. Inositol-1-monophosphate (0.5 mM) and cyclic-inositol-(1:2)-monophosphate (0.5 mM) enhanced their Km value by at least 30 percent compared to p-nitrophenylphosphate

Inhibition of rabbit intestinal brush border sucrase by indolin 2,3-dione (isatin) at pH 5.0.

Isatin (10 mM) inhibited the activity of rabbit brush border sucrase by 60% at pH 5.0 but it had no effect on enzyme activity around neutral pH. Isatin inhibition of sucrase was unaffected by Na+ ions but K+ and Cs+ ions reduced enzyme inhibition, partially. Kinetic analysis revealed that sucrase inhibition by isatin at acidic pH was non-competitive with Ki of the order 6.5-7.8 mM. Isatin together with 4 mM harmaline or iodoacetate (3 mM) or dithionitrobenzene (2 mM) yielded 80-85% inhibition of the enzyme. These observations suggest that inhibitory sites for isatin, harmaline and -SH group reacting agents are distinct in rabbit brush border sucrase.

Structural and immunological studies of GPI-anchored brush border hydrolases

The complement of brush border hydrolases provides an excellent model system for study of the structure, topology and assembly of plasma membrane proteins. Among the peptidases of the renal brush border are a number of glycosylphosphatidylinositol (GPI)-anchored proteins, especially membrane dipeptidase and aminopeptidase P. Affinity purification protocols have led to the isolation of homogeneous forms of these proteins and membrane dipeptidase has been cloned and expressed in Xenopus oocytes and Cos-1 cells. The core glycan structures of both human and porcine dipeptidase have been determined, allowing direct comparisons of the GPI anchors on the same protein in different species. Aminopeptidase P has been compared in the brush borders of pig kidney and intestine and may well be anchored in distinct ways in the two tissues. Immunological cross-reactivity of polyclonal antibodies to these two proteins has revealed the phospholipase C-cleaved GPI anchor as the common epitope and defined those components of the anchor important for recognition. These antibodies are also proving useful in characterizing GPI-derived mediators that may be involved in cell signalling processes. These abundant ectopeptidases offer a number of advantages for studies of the biochemistry of mammalian GPI anchors

Effect of feeding high fat, high fiber diet on brush border enzymes in mice intestine.

The effect of dietary fat content on brush border enzymes has been studied in mice intestine. The results obtained from 26 per cent fat (high fat; HF)-fed mice were compared with those fed 10 per cent fat (pair-fed; PF and ad libitum-fed). Brush border alkaline phosphatase (AP), leucineaminopeptidase (LAP) and gamma-glutamyltranspeptidase (gamma-GTP) activities were significantly enhanced while sucrase activity was reduced (P < 0.001) in HF group compared to the controls. Activities of lactase, p-nitrophenyl (PNP)-beta-D-glucosidase and PNP-beta-D-galactosidase were unaltered under these conditions. Kinetic studies with AP, sucrase and LAP revealed that changes in enzyme levels in response to HF diet were due to change in Vmax. Significant changes in enzyme activities as a consequence of HF intake were observed in enterocytes all along the crypt-villus unit as compared to the control group. These results indicated that feeding a fat-rich diet produced selective changes in brush border enzyme activities in mice intestine.

Aislamiento de isoenzimas de fosfatasa alcalina en plasma humano, por cromatografía de intercambio iónico / Alkaline phosphatase isolation isoenzymes in human plasma ionic chromatography

A partir de la preparación de fosfatasa alcalina (EC 3.1.3.1) parcialmente purificada con etanol, de plasma de personas con grupo 0, se separaron cuatro fracciones con actividad enzimática, mediante cromatografía en columna de DEAE-celulosa, con gradiente discontinuo de NaCI. También se extrajo fosfatasa alcalina de hígado, hueso y mucosa intestinal humanos, a fin de caracterizar las distintas formas moleculares. el uso de inhibidores (L-fenil-alcalina y urea) y electroforesis en gel de poliacrilamida, permitió identificar las isoenzimas presentes en los extractos de tejidos y en los picos de elución cromatográfica de la enzima de plasma. La isoenzima hepática se encuentra en todas las fracciones. La primera eluye con NaCI 40 mM y puede separarse en dos (IA e IB). Ambas contienen las isoenzimas intestinal y ósea, además de formas parcialmente desializadas de la hepática. La segunda fracción (NaCI 60 mM) contiene exclusivamente fosfatasa alcalina hepática. La tercera (NaCI 200 mM), de alto peso molecular, está compuesta por las isoenzimas ósea, intestinal y hepática. El perfil es muy reproducible. La comparación del cromatograma correspondiente a plasma normal con el de un paciente portador de un tumor con metástasis óseas, muestra notables diferencias, indicando la utilidad diagnóstica del método, ya que permite identificar el órgano de origen, en casos de incremento de fosfatasa alcalina en plasma.

Kinetic properties of gamma-glutamyltranspeptidase and leucine-amino-peptidase in developing rat intestine: effect of hormones.

Administration of cortisone and thyroxine produced adult-type increase in the activities of soluble and membrane-bound gamma-glutamyltranspeptidase (gamma-GTP) in suckling rat intestine. Membrane-bound enzyme activity remained unaltered while the soluble enzyme activity was reduced (27%) in insulin-injected pups. Kinetic analysis revealed that the observed changes in the enzyme levels were a consequence of altered Vmax with no change in apparent Km. A 2-fold increase in the Km value was observed in adult gamma-GTP activity compared to that of suckling animals. Membrane-bound and soluble gamma-GTP yielded similar values of the Ea (9.7-13.1 kcal/mole) but exhibited apparent differences in heat stability in the control and hormone-injected groups. Leucine-amino peptidase(LAP) activity was reduced to adult levels in insulin-treated suckling animals. Thyroxine- and cortisone-treatment did not affect soluble activity but significantly (P less than 0.001) augmented the membrane-bound LAP levels. This increase was due to enhanced (54-82%) Vmax with no change in Km. The observed decrease in LAP activity in response to insulin was due to reduced Vmax. There was no change in Ea (8-11.6 kcal/mole) except the value was raised to 19.1 kcal/mole in cortisone-injected pups. Both the soluble and membrane-bound LAP activities were quite resistant to heat inactivation upto 30 min at 60 degrees C except in weanling rats. Thus, the kinetic behaviour of normally developed and precociously induced gamma-GTP and LAP is essentially similar but there are apparent differences in the mode of action of insulin, cortisone and thyroxine in affecting the development of these enzymes.

Effect of various doses of medroxyprogesterone acetate on intestinal functions in rats.

The dose relationship between medroxyprogesterone acetate (MPA), a long acting contraceptive, and rat intestinal digestive and absorptive functions has been investigated. The study revealed that the activities of brush border sucrase, lactase and leucine aminopeptidase were stimulated only at high doses, viz 70 mg/kg (180 mumol/kg) body weight and above, whereas the activity of alkaline phosphate was depressed at comparatively low dose (17.5 mg/kg; 45 mumol/kg body weight). This decrease was found to be significant (p less than 0.001) at all the doses tested. The inhibition in the intestinal uptake of calcium paralleled the decrease in alkaline phosphatase activity. Relatively high amount of MPA (140 mg/kg; 360 mumol/kg) was required to augment the uptake of glucose and amino acid. The results obtained do not indicate a close relationship between the dose of the drug and the extent of alteration in the rat intestinal digestive and absorptive functions. The study appears to confirm the association between brush border enzymes activities and uptake of nutrients in rat intestine.

Efecto de la ingestión de pan integral sobre la actividad disacaridasica intestinal en ratas / Effects if ingestion of whole-wheat bread on intestinal disacharidase activity in rats

Se realizó un experimento para evaluar el efecto de la ingestión de pan integral sobre la actividad disacaridásica intestinal. Se utilizó un total de 21 ratas macho, las cuales se agruparon según: a) dieta control con caseína más metionina, b) dieta con blanco, y c) dieta con pan integral. Despúes del periodo experimental de 10 días, se determinó la actividad específica de lactasa, mitasa, sacarasa y trealasa en distintos niveles de localización en la microvellosidad. Todas las enzimas presentaron una disminución significativa (p<0,01) de su actividad en la fracción luminal en las ratas alimentadas con pan integral. Sólo la lactasa y la maltasa mostraron una disminución de su actividad (p<0.01) en la fracción de membrana para dicha dieta. La fracción enterocitaria no mostró diferencia cuando se comparó con la dieta de pan blanco. En todos los nivles de localización la actividad disacaridásica fue mayor en la dieta control (p<0.01). Los resultados obtenidos sugieren que el efecto por "arrastre mecánico" de la fibra dietética contenida en el pan integral es el fundamental en la interacciòn fibra-actividad disacaridásica y que, por tanto, su presencia en el intestino no afecta sensiblemente la biosíntesis de dichas enzimas en el enterocito